Health & Physical Education

On 7 January 2026 the United States Department of Health and Human Services and the United States Department of Agriculture published new national food advice, and the picture on the front was a pyramid standing on its point. It is the tenth edition of the Dietary Guidelines for Americans, covering 2025 to 2030, and it retired MyPlate, the divided dinner plate that had been the official picture since June 2011.

An upside-down pyramid is a strange shape until you work out what it is doing. In an ordinary food pyramid the widest band sits at the bottom, and the widest band is what you are meant to eat most of. Turn the pyramid over and the widest band is now at the top. So on this one, the band at the top is the one you eat most from.

The three tiers, and the numbers attached to them

One warning about the protein number before you reach for a calculator. The guidelines print it as a single target and do not publish a separate figure for eleven-year-olds. Your body is still growing, which changes the arithmetic, and a school nurse or a doctor is the person who can turn a general target into a number that fits you. Use the serving counts as your everyday tool and treat the protein figure as the direction of travel: some real protein at every meal.

Key idea: The 2025-2030 edition puts protein, dairy and healthy fats in the widest band and whole grains at the narrow point. That is a genuine change from the plate you may have seen in an earlier year, not a redrawing of the same advice.

What one serving actually is

A serving is a fixed measured amount, set so that everyone counts the same way. It is not the same as a portion, which is however much you happen to put on your plate. A restaurant portion of rice can easily be four servings.

You can estimate servings with your own hand, which is convenient because your hand grows as you do.

• Cut vegetables or fruit: what fits in your cupped hand, about half a cup.
• Leafy salad: about two cupped hands, because leaves are mostly air.
• Cooked grain: your closed fist is about a cup, which is two servings.
• Meat or fish: the size and thickness of your palm.
• Nuts: a small handful, not a fistful.

Why protein gets the widest band

Protein is the raw material your body builds with. Muscle, skin, hair, the enzymes that digest your lunch and the antibodies that fight an infection are all built from protein, and they are rebuilt constantly. Between eleven and fourteen you are adding height and muscle faster than at any time since you were a toddler, so the building site is busy.

Protein also keeps you full longer than the same calories of sugar, which is why eggs hold until lunch and sweetened cereal often does not. Dairy and fats share the band because fat does jobs nothing else can: it builds the outer wall of every cell in you, and vitamins A, D, E and K cannot be absorbed without it.

What vegetables and fruit do that a vitamin tablet does not

Vegetables and fruit carry vitamins and minerals, but they also carry dietary fibre, the part of a plant your body cannot digest. Fibre sounds useless until you notice what it does on the way through: it slows down how fast sugar reaches your blood, it feeds the bacteria in your large intestine, and it keeps things moving.

This is the honest reason an orange and a glass of orange juice are not the same food. The orange brings its fibre with it. Juicing throws the fibre away and leaves the sugar, which is why the guidance says whole fruit, in its original form.

The point: Whole beats extracted. The useful parts of a plant food are not only the ones a laboratory can name and put in a tablet.

Whole grain against refined, and the part that gets thrown out

A grain of wheat has three parts: the bran, which is the tough outer coat; the germ, which is the seed that would grow into a plant; and the endosperm, the starchy middle that feeds the seed. Whole grain flour contains all three. White flour is the endosperm only, with the bran and germ milled out.

What leaves with the bran and germ is most of the fibre and a good part of the B vitamins and minerals. What stays is starch, which your body breaks down into sugar quickly. That is the whole of the difference between brown and white bread, and it is why the new guidance says whole grains are encouraged and refined carbohydrates are not.

The new part of this edition: highly processed food

For the first time, the guidelines name a category of food to avoid rather than only naming foods to eat. The wording is highly processed food, and the guidance describes it as packaged, prepared or ready-to-eat food that is salty or sweet, such as chips, cookies and candy carrying added sugars and salt, along with refined carbohydrates and chemical additives.

Notice what processing is not. Freezing peas is processing, and so are pasteurising milk, canning beans and cutting a carrot. None of those is the target. The target is food rebuilt from cheap components into something engineered to be eaten fast and in quantity, with the fibre gone and the sugar, salt and fat dialled up.

A test that works in a shop: read the ingredients list. If it is short and you recognise everything on it as food, you are probably holding food. If it runs to twenty items, several of them sugars under different names, you are holding a product.

One ordinary day, measured against the pyramid

That day is not a disaster and nobody should be told it is. It lands 2 vegetable servings out of 3, 1 fruit out of 2, and 0 whole grains out of 2 to 4. Three cheap fixes are visible from the table: brown bread for white, brown rice for white, and a second piece of fruit. None of those requires a diet or giving anything up.

Worth holding on to: Compare a real day against the numbers and the change that matters usually turns out to be a swap, not a ban.

Common misconceptions

• "Carbohydrates make you fat." Carbohydrate is your ordinary fuel, and the guidelines still ask for 2 to 4 servings of whole grains a day plus all the carbohydrate in fruit and vegetables. The advice is against refined carbohydrate and added sugar, a much narrower target.
• "Fat is the enemy." This edition puts healthy fats in the widest band, beside protein and full-fat dairy. Fat builds cell walls and carries vitamins A, D, E and K into you.
• "Foods are either healthy or junk." No single food decides anything. The guidance is about what your week mostly looks like.

The short version

The Dietary Guidelines for Americans 2025-2030, published in January 2026 by HHS and USDA, replaced MyPlate with an inverted pyramid: protein, dairy and healthy fats in the widest band at the top, vegetables and fruits in the middle at 3 and 2 servings a day, whole grains at the narrow point at 2 to 4 servings. A serving is a fixed measure you can estimate with your hand; a portion is whatever you took. Whole grain beats refined because the bran and germ stay in, and whole fruit beats juice because the fibre travels with it. This edition is the first to name highly processed food as something to reduce, meaning packaged sweet and salty products built from refined ingredients, not frozen peas.

Sources

1. U.S. Department of Health and Human Services and U.S. Department of Agriculture. (2026). Dietary Guidelines for Americans, 2025-2030 (10th ed.). realfood.gov
2. Office of Disease Prevention and Health Promotion. (2026). Current Dietary Guidelines. ODPHP, U.S. Department of Health and Human Services. odphp.health.gov
3. World Health Organization. (2020). Healthy diet fact sheet. WHO. who.int
4. Wikipedia contributors. (n.d.). MyPlate. Wikipedia. en.wikipedia.org

Pick up a 12 fluid ounce can of Coca-Cola and turn it so the Nutrition Facts panel faces you. Four numbers on it do almost all the work: 1 serving per container, 140 calories, 39 grams of total sugars, and 39 grams of added sugars carrying a percent Daily Value of 78.

That last figure means one can uses up 78 percent of a whole day's added sugar allowance. Nothing on the front of the can says so. The panel is where that fact lives, and reading a panel is a skill with a fixed order of operations, like long division.

Step one, before anything else: serving size

The top two lines are servings per container and serving size. Every other number on the panel describes one serving, and only one serving.

The United States Food and Drug Administration is blunt about what a serving size is not. In its guidance on using the label, updated in March 2024, it explains that serving sizes are standardised so you can compare similar foods, and that the serving size is not a recommendation of how much you should eat or drink. It is a measuring unit, not permission and not a limit.

This is the single most common place people misread a package. A bottle, a bag or a tub that holds three servings prints one serving's numbers. If you drink or eat the whole thing, every number on that panel gets multiplied by three, including the calories and the added sugars.

In short: Read servings per container first, every time. Until you know that number, the rest of the panel means nothing.

Step two: calories, and what they are

A calorie is a unit of energy. The panel counts the energy your body can get from one serving. The FDA prints the whole panel against a 2,000 calorie day as a general reference, and states plainly that your own needs may be higher or lower depending on age, sex, height, weight and how active you are. A fourteen-year-old who trains most days does not eat like the reference figure, and is not supposed to.

Calories are not a measure of how good a food is. Almonds are calorie-dense and useful. A fizzy drink has fewer calories than the almonds and brings nothing else with them.

Step three: the two groups of nutrients

The middle of the panel is split into things to limit and things to get enough of. The daily reference amounts, all set against 2,000 calories, are worth knowing by heart because they turn any gram figure into a judgement.

Added sugars deserve their own line on the panel because they are different from the sugar already in a food. The sugar in milk and the sugar in an apple arrive wrapped in protein, calcium, water and fibre. Added sugar is sugar a manufacturer put in. Total sugars counts both; added sugars counts only what was put in. On a cola the two figures are identical, because every gram of it was added.

Step four: percent Daily Value, and the 5 and 20 rule

Beside most nutrients is a percentage. It answers one question: how much of a day's reference amount does one serving of this contain?

The FDA gives a two-number rule for reading those percentages quickly. Five percent Daily Value or less per serving is low. Twenty percent or more is high. That is the whole rule, and it works in either direction: low is good for sodium and saturated fat, and bad for fibre.

Run the cola through it. 39 grams of added sugars against a 50 gram reference is 39 divided by 50, which is 0.78, or 78 percent. Anything above 20 is high, so 78 is nearly four times the threshold for high, from one drink.

Why this matters: The percentage does the arithmetic you would otherwise have to do in your head, and the 5 and 20 rule turns that percentage into a decision in about a second.

The same maths on a package that holds more than one serving

Here is a panel of the kind printed on a snack bag. Work it through, then look at what changes.

One serving looks moderate. Sodium at 8 percent is between the two thresholds, so it is neither low nor high. Eat the bag, which is what usually happens to a bag, and sodium lands at 24 percent and saturated fat at 23. Both cross into high. Nothing about the food changed. Only the multiplier did.

The ingredients list is a ranking

Under the panel sits the ingredients list, and it follows one rule: ingredients are listed in order of weight, heaviest first. So the first three items are most of what you are holding.

Sugar can be split across several names, which pushes each one further down the list. Watch for sucrose, high fructose corn syrup, dextrose, maltose, cane juice, fruit juice concentrate, honey and molasses. Four of them at positions five to eight can add up to more than the ingredient sitting at position two.

Common misconceptions

• "The calorie number is for the whole package." It is for one serving. A package holding 2.5 servings at 230 calories each is 575 calories if you finish it.
• "The serving size is how much I should eat." The FDA says directly that it is not a recommendation. It is a standard measure so you can compare two products fairly.
• "No added sugars means no sugar." Total sugars and added sugars are separate lines. A carton of plain milk has grams of total sugar and zero added.

What to carry forward

Read a panel in order: servings per container, then serving size, then everything else, because every figure below describes one serving only. Calories measure energy, against a 2,000 calorie reference that will not match everyone. Four daily reference amounts do most of the judging: 50 grams of added sugars, 2,300 milligrams of sodium, 20 grams of saturated fat, and 28 grams of fibre. Percent Daily Value converts grams into a fraction of a day, and 5 percent or less is low while 20 percent or more is high. A 12 ounce can of cola carries 39 grams of added sugars, which is 78 percent of a day. Multiply the panel when the package holds more than one serving, and read the ingredients list as a ranking by weight, watching for sugar split across several names.

Sources

1. U.S. Food and Drug Administration. (2024, March 5). How to understand and use the Nutrition Facts label. FDA. fda.gov
2. U.S. Food and Drug Administration. (n.d.). Added sugars on the Nutrition Facts label. FDA. fda.gov
3. The Coca-Cola Company. (n.d.). Ingredients: how much sugar is in Coca-Cola. The Coca-Cola Company. coca-colacompany.com
4. U.S. Food and Drug Administration. (n.d.). Daily Value on the Nutrition and Supplement Facts labels. FDA. fda.gov

Before you read: write down every drink you had yesterday, including water, and roughly how much of each. Keep the list beside you. You will use it twice.

Here is a sentence almost everyone in a school corridor believes: after PE you need a sports drink, because you have sweated and you need to replace what you lost. It sounds like physiology. Follow it step by step and you can see exactly where it stops being true.

What a sports drink was designed to do

A sports drink contains three things: water, carbohydrate as sugar, and electrolytes, which are minerals such as sodium and potassium that carry an electrical charge and that your nerves and muscles need in order to fire. Sweat carries out water and some sodium. If you sweat hard for a long time, replacing both together helps.

Those drinks were built for endurance athletes: long, continuous, hard effort, often in heat. That is the situation the design solves.

Where the reasoning breaks

A PE lesson is not that situation. It is forty minutes, mostly stop and start, usually indoors or in mild weather, and you have eaten within a few hours. The American Academy of Pediatrics looked at exactly this question in a clinical report on sports and energy drinks for children and adolescents. For most children in routine physical activity, its conclusion was that the drink of choice is plain water, and that sports drinks add calories a young athlete does not need.

So the sentence fails not because sports drinks are fake, but because the conditions the drink is for are missing. The reasoning applies a solution to a problem you did not have. Where they do make sense: continuous hard effort lasting well over an hour, or training in real heat. A cross-country runner in July is a different case from a Tuesday PE class.

The point: A product can be genuinely useful and still be the wrong answer for you, because the thing it fixes is not happening to you.

Energy drinks are a separate category, and the answer is simpler

An energy drink is not a sports drink. It contains stimulants, usually caffeine, often in large amounts and sometimes not clearly labelled. The same AAP report is unusually blunt about these: stimulant-containing energy drinks have no place in the diets of children or adolescents. Caffeine in a body that is still growing raises heart rate and blood pressure, and it wrecks sleep, which the next module will show is expensive in ways you feel at school.

Turning grams into teaspoons

Grams of sugar are hard to picture. Teaspoons are not. One level teaspoon of granulated sugar weighs about 4 grams, so dividing the grams on a panel by 4 gives you a number you can see.

Now the comparison that matters. In a 2017 scientific statement, the American Heart Association recommended that children and teenagers aged 2 to 18 take in less than 25 grams of added sugars a day, about 6 teaspoons, and drink no more than one 8 ounce sugar-sweetened drink a week.

One 12 ounce can of cola is 39 grams. That is more than one and a half times the entire daily limit, and it is one drink, and the limit is for a whole day of food as well as drink.

Bottom line: Sugary drinks are the single easiest place to lose the day's added sugar budget, because a drink does not make you feel full the way food does.

How much water do you actually need?

Less precisely than the internet claims. The CDC's guidance on water and healthier drinks, reviewed in March 2026, says daily water intake recommendations vary by age, sex, activity level and other factors, and it does not hand out a fixed number of glasses. The famous eight glasses a day is not a federal recommendation.

Two practical signals work better than a number.

• Thirst. In a healthy young person, thirst is a reliable prompt. Drink when you are thirsty, and drink extra before and during sport in the heat, when thirst lags behind what you have lost.
• Urine colour. Pale straw means you are fine. Dark yellow means drink more. This is a rough check, not a diagnosis, and some vitamins turn urine bright yellow regardless.

Dehydration is not a vague complaint. The CDC lists unclear thinking, mood change, overheating, constipation and kidney stones among its effects. The fuzzy, irritable feeling in a hot afternoon lesson is sometimes just water.

The diet aimed at you

Scroll any feed for ten minutes and something will offer a fourteen-year-old a plan: a fat-burning tea, a detox, a supplement, a set of rules about what not to eat after seven. Three things are worth knowing about that industry.

First, the products are not tested the way medicines are. The FDA does not approve dietary supplements for safety and effectiveness before they go on sale. The company is responsible for its own claims. A bottle on a shelf has cleared no safety check like the one a prescription drug clears.

Second, deliberate dieting in adolescence is a documented risk, not a neutral choice. A 2016 clinical report in Pediatrics, written for doctors who see teenagers, concluded that dieting is a risk factor for both obesity and eating disorders, and advised against it. Restricting food during the years you are building bone and height has a cost that the marketing never mentions.

Third, eating disorders are real medical illnesses, not vanity or a phase. The National Institute of Mental Health describes them as serious and treatable conditions that often begin in the teenage years, and treatment works better the earlier it starts.

So here is the line to remember. If what you eat, or how your body looks, is taking up a large share of your thinking, or you are hiding food, skipping meals on purpose, or exercising to make up for eating, tell someone: a parent or carer, the school nurse, a school counsellor, or your doctor. You are not asking them to put you on a plan. You are asking them to look at it with you, which is a different and much easier request.

Common misconceptions

• "Sports drinks are needed for ordinary exercise." For routine activity the AAP says the drink of choice is water. Sports drinks are for prolonged hard effort or real heat.
• "Everyone needs eight glasses of water a day." The CDC gives no fixed number, because needs vary by age, sex and activity. Thirst and urine colour are better guides.
• "Fruit juice is as good as fruit." Juice keeps the sugar and loses the fibre. Whole fruit is the form the guidelines ask for.

Where this leaves us

Sports drinks solve a real problem, which is fluid, carbohydrate and electrolyte loss during long, hard, hot effort, and a PE lesson is not that problem. Energy drinks are a different product containing stimulants, and the AAP says they have no place in a young person's diet. Divide grams of sugar by 4 to get teaspoons: a 12 ounce can of cola is 39 grams, about 10 teaspoons, while the American Heart Association's 2017 statement puts the whole daily limit for ages 2 to 18 at under 25 grams and at most one 8 ounce sugary drink a week. There is no official eight glasses rule; drink to thirst, check urine colour, and drink more in heat and sport. Supplements are not pre-approved by the FDA, deliberate dieting in adolescence is itself a risk factor, and if food or your body is occupying your thinking, that is a thing to say out loud to an adult who can help.

Sources

1. Committee on Nutrition and the Council on Sports Medicine and Fitness, American Academy of Pediatrics. (2011). Sports drinks and energy drinks for children and adolescents: Are they appropriate? Pediatrics, 127(6), 1182-1189.
2. Vos, M. B., Kaar, J. L., Welsh, J. A., et al. (2017). Added sugars and cardiovascular disease risk in children: A scientific statement from the American Heart Association. Circulation, 135(19), e1017-e1034.
3. Centers for Disease Control and Prevention. (2026, March 5). About water and healthier drinks. CDC. cdc.gov
4. Golden, N. H., Schneider, M., Wood, C., et al. (2016). Preventing obesity and eating disorders in adolescents. Pediatrics, 138(3).
5. National Institute of Mental Health. (n.d.). Eating disorders. NIMH. nimh.nih.gov

Sixty minutes a day. That is the number the United States government attaches to every person aged 6 through 17, and it comes from the Physical Activity Guidelines for Americans, second edition, published in 2018 and restated by the CDC in its guidance last reviewed on 4 December 2025.

A number on its own is not much use. Sixty minutes of what? Does walking to school count? Does it have to be one block of time? Does anything happen if you do fifty? Work through those questions and the guideline turns into something you can actually use.

The guideline in four lines

Read the middle column again. The last three requirements sit inside the 60 minutes, not on top of it. A basketball game does all four at once: it is aerobic, it is vigorous in bursts, the jumping loads the bones and the sprinting and holding position load the muscles. This is why sport is efficient, not magic.

The 60 minutes also does not have to be one block. Fifteen minutes walking to school, twenty in PE, ten of stairs and errands and fifteen kicking a ball after dinner is sixty minutes.

What matters here: Four requirements, one time budget. The daily 60 is the container; vigorous, muscle and bone work are things you put in it three days a week.

Moderate or vigorous: two ways to tell

Intensity is relative. The same jog is easy for one person and hard for another, so the guidance measures effort rather than speed. The CDC gives two tests.

The first is a scale of 0 to 10, where 0 is the effort of sitting still and 10 is maximal effort. Moderate intensity is 5 or 6. Vigorous begins at 7 or 8.

The second is the talk test, and you can run it on yourself mid-activity without any equipment. A person doing moderate-intensity activity can talk, but not sing. A person doing vigorous-intensity activity cannot say more than a few words without pausing for a breath.

Try it during your next PE lesson. Most people discover that what they thought was vigorous is comfortably moderate, because they can hold a conversation the whole way through.

Aerobic work, and what it changes

Aerobic means with oxygen. Aerobic activity is anything that keeps large muscles moving long enough that your heart and lungs have to work harder to deliver oxygen to them. Running, swimming, cycling, dancing, brisk walking uphill.

The heart is a muscle, and like any muscle it adapts to being asked to work. A heart that trains regularly pushes more blood with each beat, which is why fit people have lower resting heart rates, a number you will measure in the next lesson.

There is also a same-day effect that has nothing to do with fitness. The CDC states that some brain-health benefits happen right after a single session of moderate-to-vigorous activity, including improved thinking or cognition in children aged 6 to 13. That is not a claim about becoming smarter over a year. It is a claim about this afternoon.

Muscle-strengthening is not the same as weightlifting

Muscle-strengthening activity is anything that makes a muscle work against a resistance more than it usually does. Your own body weight counts and is the obvious place to start: push-ups, pull-ups, squats, planks, climbing, carrying something heavy up stairs. The CDC's own examples for this age group are climbing and push-ups, which need no equipment at all.

Three days a week is the requirement, and the days do not need to be consecutive. Muscle repairs and rebuilds in the gap between sessions, so the rest day is part of the training rather than a break from it.

Bone-strengthening: the part nobody mentions

Bone is living tissue. The National Institute of Arthritis and Musculoskeletal and Skin Diseases puts it plainly: your bones respond to exercise by making new bone tissue, which helps keep them strong. Its examples of activity that does this are basketball, kickball, walking, jumping rope and dancing, all of which share one feature. Your feet hit the ground.

Timing matters here more than anywhere else in this lesson. The amount of bone tissue in the skeleton peaks in most people by their mid to late twenties. What you build now is the peak you spend the rest of your life drawing down from. Jumping rope for five minutes is a deposit into an account you cannot top up later in the same way.

Remember: Aerobic work trains the heart, resistance work trains muscle, impact trains bone. They are three different stimuli and no one of them substitutes for the others.

Flexibility, and honesty about what the guideline says

Stretching and mobility work are not part of the four requirements above. The guideline does not set a flexibility target for your age group, and it would be dishonest to pretend it does. What flexibility work does is keep joints moving through their full range, which matters for how comfortably you sit, reach and move, and it is the cheapest thing in this lesson to add: a few minutes after activity, when muscles are warm.

What counts, which is more than most people think

• Walking or cycling to school, if it is brisk enough to pass the talk test at moderate.
• PE, break time and any game involving running.
• Dancing, skateboarding, swimming, martial arts, climbing.
• Carrying shopping, mowing a lawn, shovelling snow, walking a dog fast.
• Chasing a younger sibling around a garden, which is interval training with a different name.

What does not count is time spent sitting between the good bits. The point of listing ordinary activity is not to let you off; it is that people badly underestimate their own day in both directions.

Common misconceptions

• "Only proper sport counts." The guideline counts any moderate-to-vigorous activity. Walking fast to school is aerobic activity whether or not anyone is keeping score.
• "It has to be 60 minutes in one go." It does not. Activity accumulates across the day.
• "Strength training will stunt your growth." The guideline actively asks for muscle-strengthening activity three days a week for ages 6 to 17, using body weight and climbing as its examples.

Putting it together

The Physical Activity Guidelines for Americans, second edition, 2018, ask anyone aged 6 to 17 for 60 minutes or more of moderate-to-vigorous activity every day, with vigorous activity, muscle-strengthening and bone-strengthening each appearing at least 3 days a week inside that hour. Intensity is judged by effort, not speed: 5 to 6 out of 10 is moderate and you can talk but not sing, 7 to 8 is vigorous and you cannot say more than a few words without a breath. Aerobic work trains heart and lungs and improves thinking in the hours right after a session. Resistance work needs no equipment. Impact activity builds bone, and bone mass peaks by the mid to late twenties, so the deposits you make now are the ones you keep. The 60 minutes accumulates across a day, and ordinary movement counts toward it.

Sources

1. Centers for Disease Control and Prevention. (2025, December 4). Child activity: An overview. Physical Activity Basics, CDC. cdc.gov
2. Centers for Disease Control and Prevention. (2025, December 4). How to measure physical activity intensity. Physical Activity Basics, CDC. cdc.gov
3. U.S. Department of Health and Human Services. (2018). Physical Activity Guidelines for Americans (2nd ed.). odphp.health.gov
4. National Institute of Arthritis and Musculoskeletal and Skin Diseases. (2025, June). Health lesson: Learning about bones. NIAMS, National Institutes of Health. niams.nih.gov

Do this before reading further. Place your index and middle finger on the underside of your opposite wrist, below the base of the thumb, and press with flat fingers until you feel a beat. Count the beats for 30 seconds and double the number. That is your heart rate right now, and the technique is exactly the one the MedlinePlus medical encyclopedia describes.

This lesson is a procedure in four steps: measure, warm up, build up, and know the point at which you stop. Each step is something you do, not something you know.

Step 1: resting heart rate, and what the number is worth

Resting heart rate means your heart rate when you are genuinely at rest, which is not the same as when you are sitting down having just run up the stairs. Take it first thing in the morning before you get out of bed, or after sitting still for five minutes.

Two things this number is good for. Over months, a resting heart rate drifting down while everything else stays the same is a sign that aerobic training is working, because a stronger heart moves more blood per beat and therefore needs fewer beats. Day to day, a resting rate well above your own normal often means you slept badly, are getting ill, or are under strain, all of which are reasons to train easier.

One thing it is not good for: comparing yourself with a friend. The normal range for your age is forty beats wide. Inside that range, a difference between two people means very little.

The core of it: Track your own number over time. It is a signal about you, not a score against anyone else.

Step 2: the warm-up, and what it is actually doing

A warm-up raises the temperature of your muscles, increases the blood flowing through them, and rehearses the movements you are about to make faster. Cold muscle is stiffer and less responsive than warm muscle, which is the whole physiological reason the practice exists.

A workable warm-up takes five to ten minutes and has two halves. First, an easy version of what you are about to do: jog before you sprint, gentle rally before a match. Second, movement through the range you will use at speed: leg swings, arm circles, lunges, a few gradually faster efforts.

Be clear about the status of that routine. The National Institute of Arthritis and Musculoskeletal and Skin Diseases lists increasing the intensity of physical activity too quickly and overtraining among the risk factors for sports injury. It does not publish a warm-up prescription, so treat the five to ten minute routine as sensible practice, not as a rule handed down from a guideline.

Step 3: build up, and the mistake almost everyone makes

The most common way a healthy young person gets hurt is not a dramatic collision. It is doing too much, too soon. NIAMS separates injuries into two kinds: acute ones, which happen suddenly when a person falls, takes a blow or twists a joint, and chronic ones, which usually come from overusing one area of the body.

Overuse injuries are the avoidable kind, and they are avoided by adding work slowly. Coaches commonly use a ten percent rule: increase your weekly total by about a tenth, no more. It is a rule of thumb rather than a published guideline, but it captures the right idea, which is that tissue adapts on a slower timetable than enthusiasm.

A worked build-up, four weeks of running

Notice week 4. Dropping back every third or fourth week is deliberate. The adaptation happens during the easier stretch, not during the hard one.

Change one input, and the plan breaks

Keep the running plan exactly as it is, and add one thing: basketball training on three evenings a week starting in week 2. The running total still rises by a careful ten percent. The total load on the same ankles, shins and knees roughly doubles in a week.

That is the trap. Progression applies to everything your legs do added together, not to one activity at a time. If a new sport, a new season or a school team arrives, the sensible move is to hold the other training flat, or cut it, while your body absorbs the new thing.

So what?: Count total load, not one training plan. Bodies do not know which activity a stress came from.

Soreness or injury?

Muscle soreness that appears 24 to 48 hours after unfamiliar work, sits on both sides of your body, feels like a dull ache, and eases once you start moving again is ordinary. It is called delayed onset muscle soreness and it is not damage you need to worry about.

An injury behaves differently. NIAMS describes a sprain as an injury to a ligament, the tissue joining bone to bone, ranging from minimal stretching to a partial or complete tear. A strain involves a muscle or a tendon instead. Both tend to be one sided, sharp rather than dull, and worse when you use the part rather than better.

The stop list

Stop immediately, and tell a coach, a PE teacher or a parent, if any of these happen.

• Pain that makes you change how you move, or that is sharp and in one spot.
• A joint that gives way, locks, or swells quickly.
• Chest pain, or feeling faint or dizzy.
• Any knock to the head, however small it seemed at the time.

The head one deserves its own paragraph. A concussion is a brain injury and it does not always knock someone out. The CDC's HEADS UP guidance lists, for ages 5 to 17, appearing dazed or confused about recent events, answering questions more slowly than usual, and seeming unsteady on the feet, along with headache, dizziness or balance problems, trouble concentrating, feeling foggy, irritability and changes in sleep. The rule the CDC states about coming back is short: an athlete should only return to sports with the approval of a healthcare provider.

Common misconceptions

• "No pain, no gain." Dull soreness a day or two after new work is normal. Sharp pain during activity is information, and continuing through it is how a small problem becomes a long one.
• "A low resting heart rate always means you are fit." It can, tracked over months in one person. Across two people it means little, since the normal range at your age is forty beats wide.
• "If you can still play, it was not a concussion." Most concussions involve no loss of consciousness at all, which is exactly why the return rule depends on a healthcare provider rather than on how you feel.

What to remember

Take your pulse at the wrist with two flat fingers and count 30 seconds doubled. For age 10 and over the normal resting range is 60 to 100 beats per minute, and the number is worth tracking in yourself rather than comparing with a friend. Warm up for five to ten minutes with an easy version of the activity and then movement through the range you will use, understanding that this is sensible practice rather than a published rule. Build up gradually, because NIAMS names increasing intensity too quickly and overtraining among the risk factors for injury, and count the total load across everything you do rather than one plan at a time. Ordinary soreness is late, dull, on both sides and eases with movement; injury is immediate, sharp, one sided and worse with use. Stop for sharp pain, a joint giving way, chest pain, faintness, or any knock to the head, and after a head injury return to sport only with the approval of a healthcare provider.

Sources

1. MedlinePlus. (2025, January 1). Pulse. MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine. medlineplus.gov
2. National Institute of Arthritis and Musculoskeletal and Skin Diseases. (2024, September). Sports injuries: Types, symptoms and risk factors. NIAMS, National Institutes of Health. niams.nih.gov
3. Centers for Disease Control and Prevention. (2025, September 15). Signs and symptoms of concussion. HEADS UP, CDC. cdc.gov
4. Centers for Disease Control and Prevention. (2026, February 6). HEADS UP guidelines and recommendations. CDC. cdc.gov

Set an alarm for 06:45 and count backwards. The National Heart, Lung, and Blood Institute, part of the National Institutes of Health, recommends 9 to 12 hours of sleep a day for children aged 6 to 12, and 8 to 10 hours for teenagers aged 13 to 18. Take the bottom of the range for a twelve-year-old: 9 hours. Subtract 9 from 06:45 and you land on 21:45. That is not the time to start getting ready for bed. That is the time to be already asleep.

Try the same sum on yourself with your real alarm time. Most people your age are surprised by the answer, and then surprised again when they work out how far their actual lights-out sits from it. This lesson explains where the number comes from, what quietly pushes your bedtime later without you ever deciding to stay up, and which changes are worth making.

The numbers, and who publishes them

Three things are worth noticing in that table. The first is that each row is a range, not a single target. People genuinely differ, and a person who wakes without an alarm feeling fine on 9 hours is not doing anything wrong because someone else needs 11.

The second is that the range drops as you get older. A sixth-grader and a senior in high school do not need the same amount, so the number you were told at eight is not the number that applies to you now.

The third is that these are hours per day, counted across the whole 24 hours, not hours you spend lying in bed. Time spent in bed scrolling is not sleep, and it does not count toward the number.

The American Academy of Pediatrics, the professional body for doctors who look after children in the United States, supports the sleep duration recommendations issued by the American Academy of Sleep Medicine, and its guidance for families lists what enough sleep goes with: a healthier immune system, better performance at school, better behaviour and memory, and better mental health.

The upshot: Know your own range, then count backwards from the alarm rather than forwards from the evening. The alarm is the fixed end.

The clock in your head, and what sets it

You do not decide when you feel sleepy. A piece of your brain does, on a roughly 24 hour cycle called a circadian rhythm. The word comes from Latin for about a day. A circadian rhythm is any physical, mental or behavioural change that runs on that daily cycle, and sleepiness is only one of them: body temperature, alertness and hunger all ride the same clock.

The National Institute of General Medical Sciences describes the machinery in its circadian rhythms fact sheet, last updated on 20 May 2025. The master clock is a large group of nerve cells in the brain called the suprachiasmatic nucleus, usually shortened to SCN. It sits just above the point where the nerves from your two eyes cross, which is a clue to how it works: it is wired to receive light.

That master clock controls how much melatonin your brain makes, based on how much light your eyes are receiving. Melatonin is a hormone, which means a chemical messenger released into the blood to tell other parts of the body to do something. In the evening, as the light drops, the master clock tells the brain to make more melatonin, and more melatonin makes you sleepy.

Read that chain again, because everything practical in this lesson follows from it. Light into the eyes, less melatonin. Darkness into the eyes, more melatonin, then sleep.

Why a phone at 23:00 is a lighting problem

A screen held 30 centimetres from your face is a small lamp aimed directly into the part of your body that decides what time it is. The NIGMS fact sheet states it plainly: light from electronic devices at night can confuse biological clocks. Your eyes report daylight, the master clock believes them, the melatonin signal is delayed, and you lie there at 23:30 genuinely not sleepy.

This is not a claim that phones are evil or that you lack willpower. It is a claim about physics and biology: a bright thing close to your eyes at the wrong hour tells a clock the wrong time. A book under a dim lamp is a much smaller light source pointed nowhere in particular, which is why it behaves differently.

The American Academy of Pediatrics gives a specific instruction here, and it is one of the few in this lesson with a number on it: turn screens off at least 60 minutes before bedtime. Its other family advice is unglamorous and works for the same reason: keep wake times, meals and bedtimes on a regular schedule, get daytime physical activity and bright light, and keep the bedroom cool, around 68 to 72 degrees Fahrenheit, which is about 20 to 22 degrees Celsius.

Notice that daytime bright light appears on the list alongside evening darkness. The clock is set by the contrast between the two. A day spent indoors and an evening spent under bright screens gives the SCN very little to work with.

What short sleep actually costs

The NHLBI is careful about this, and so is this lesson. Sleep deficiency, meaning not getting enough sleep or not sleeping at the right times, is linked to many long-term health problems, including heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity and depression. Linked means these things turn up together in large studies of populations. It does not mean one short night causes heart disease.

The short-term effects are easier to see in yourself, and the NHLBI notes that they look different in children than in adults. A sleep-deficient child may be overly active and have trouble paying attention, which is close to the opposite of what people expect tiredness to look like. If you have ever been told to settle down on a morning after a bad night, that is the effect.

Worth holding on to: Tiredness in someone your age often shows up as restlessness, irritability and poor concentration rather than yawning.

Six changes, ranked by how much work they take

• Fix your wake time first, including at weekends, within about an hour. A steady wake time drags the whole clock into place.
• Get outside in the morning or at break. Daytime bright light strengthens the same rhythm that evening darkness depends on.
• Put screens away 60 minutes before the hour you calculated at the start of this lesson.
• Charge your phone somewhere other than your bed. A notification at 01:00 wakes a sleeper who would otherwise never have known.
• Keep the room cool and dark. Cool and dark are both signals, not just comforts.
• Leave caffeine out of the afternoon and evening. Energy drinks and cola are covered in Lesson 3, and the timing is the part that matters here.

When a sleep problem is a medical problem

Some sleep trouble is not about routines at all. The AAP tells parents to watch for sleep problems such as loud snoring and sleep apnea, a condition in which breathing repeatedly stops and restarts during sleep, and to talk to a paediatrician about them. Pauses in breathing, choking or gasping in sleep, and being exhausted every day despite spending enough hours in bed are all reasons to tell an adult and see a doctor rather than to try harder at bedtime.

The same goes for lying awake for hours most nights, or for sleeping far more than your range and still feeling flat, which can be a sign of low mood rather than tiredness. Tell a parent or carer, the school nurse or your doctor. If you are in the United States and you are struggling badly enough that you are thinking about hurting yourself, call or text 988, the Suicide and Crisis Lifeline, which answers 24 hours a day.

Common misconceptions

• "I can catch up at the weekend." Sleeping until midday on Saturday shifts your clock later, and the NIGMS fact sheet is clear that continually shifting circadian rhythms carries its own risks. You arrive at Sunday night with a clock set for a different time zone, which is exactly why Monday is hard.
• "I only need six hours, I am just built that way." The recommended range for your age is published for your age. Feeling used to six hours is not the same as needing six hours, and the test is whether you can wake without an alarm feeling rested.
• "Screens do not affect me because I fall asleep with my phone in my hand." Falling asleep is not the only thing at stake. Evening light delays the melatonin signal, so the sleep you get starts later than it otherwise would, and your alarm does not move.
• "Time in bed is sleep." The recommendation counts sleep, not hours spent lying down with a screen. Two hours in bed awake do not go into the total.

Summing up

The NHLBI recommends 9 to 12 hours of sleep a day for ages 6 to 12 and 8 to 10 for ages 13 to 18, and the American Academy of Pediatrics supports the same duration recommendations from the American Academy of Sleep Medicine. Work backwards from your alarm to find the hour you need to be asleep. The timing of sleepiness is set by a master clock, the suprachiasmatic nucleus, which controls melatonin production according to the light reaching your eyes, so bright screens late at night delay the signal that makes you sleepy. Enough sleep goes with better attention, behaviour, memory, immune function and mental health; sleep deficiency is linked in large studies to heart disease, high blood pressure, diabetes, obesity and depression, and in children it often shows as restlessness rather than yawning. Fix the wake time, get daylight early, switch screens off 60 minutes before bed, and treat loud snoring, pauses in breathing or exhaustion despite enough hours as reasons to see a doctor.

Sources

1. National Heart, Lung, and Blood Institute. (2022, March 24). How much sleep is enough? Sleep Deprivation and Deficiency, National Institutes of Health. nhlbi.nih.gov
2. National Heart, Lung, and Blood Institute. (2022). Sleep deprivation and deficiency. National Institutes of Health. nhlbi.nih.gov
3. National Institute of General Medical Sciences. (2025, May 20). Circadian rhythms. NIGMS fact sheet, National Institutes of Health. nigms.nih.gov
4. American Academy of Pediatrics. (2026, August 7). Healthy sleep habits: How many hours does your child need? HealthyChildren.org. healthychildren.org

The American Academy of Pediatrics attaches a specific age to the first visible change in girls: breast budding at around ten, as early as eight for some, and not until thirteen for others. That is a five year spread for one event. Line up thirty twelve-year-olds and some will have finished most of what this lesson describes while others have not started any of it.

Everyone goes through puberty. It is the stretch of years in which a child's body becomes an adult body capable of reproduction, and it is run by hormones, the chemical messengers the blood carries from one organ to another. Almost every worry people your age have about it turns out to be a worry about timing, so timing is where this lesson starts.

Two timetables, and how wide normal is

Read the first row twice. The normal window for girls is five years wide and the window for boys is five years wide, and the two windows are offset from each other by about a year. Boys enter puberty roughly a year later than girls on average, which is why a seventh grade classroom can look like it contains two different age groups. It does not. It contains one age group on different schedules.

The bottom two rows are not there to frighten anybody. They are the points at which a doctor would want to take a look, because puberty that starts very early, called precocious puberty, and puberty that has not started within the usual range, called delayed puberty, both have causes worth finding. Starting at the edge of the window is not a problem. Starting outside it is a question for a doctor, and there is nothing embarrassing about the appointment.

Remember: Being early or late is a fact about your timetable, not a verdict on your body. The range is wide because human beings are.

The order things happen in

Within each pathway the changes arrive in a fairly reliable order, which the National Library of Medicine sets out on its MedlinePlus puberty page.

Some things happen to everyone. Sweat glands become far more active, body odour appears where it never used to, hair grows in new places, and skin gets oilier. Feet often grow before the rest, which is why shoes stop fitting first. The growth spurt itself lasts about two or three years, and during it you can genuinely be clumsier than you were, because limb lengths have changed faster than your sense of where your limbs are.

The menstrual cycle, explained for everybody

This section is for every reader. If you will never have a period, you will certainly know people who do, and knowing how it works is the difference between being useful and being awkward.

The American College of Obstetricians and Gynecologists describes the sequence like this. The brain signals the body to produce hormones. Those hormones cause the lining of the uterus, the organ in which a pregnancy would grow, to thicken with extra blood and tissue. One of the two ovaries then releases an egg, which is called ovulation. If the egg is not fertilised, the thickened lining is not needed, and it leaves the body through the vagina over several days. That is a period. Then the whole sequence begins again. The full loop is the menstrual cycle.

A cycle is counted from the first day of bleeding in one month to the first day of bleeding in the next. Not from the last day. From the first.

That last row is the one that saves the most worry. Irregular cycles in the first years are expected, not a sign that something has gone wrong. A gap of 24 days followed by a gap of 40 is inside the normal range.

In practice: pads stick inside underwear and are changed every few hours; tampons and menstrual cups go inside the vagina, and ACOG says a cup is removed and emptied every 8 to 12 hours. Period underwear absorbs directly. Cramps are common and come from the uterus contracting. Carrying a spare pad, or knowing which teacher keeps some, turns a possible disaster into a two minute detour.

When a period is worth a doctor's attention

ACOG names these specifically, in guidance last reviewed in November 2025:

• Bleeding heavy enough that you need to change a pad or tampon every 1 to 2 hours.
• A period that lasts more than 7 days.
• Feeling light-headed or dizzy, or having a racing pulse, in which case see a doctor right away.
• Periods that come more often than every 21 days or less often than every 45 days.
• Cycles that were regular and then become irregular for several months.

Tell a parent or carer, the school nurse, or a doctor. None of that list is rare and none of it is your fault.

Skin, sweat and the rest of the list

Oilier skin and stronger body odour are not hygiene failures, they are hormone effects, but they do change the daily routine: a shower most days, deodorant, clean socks and underwear daily, washing hair more often than you used to, and a toothbrush twice a day that does not get skipped because you are tired.

Acne deserves a paragraph of its own, because the folklore around it is mostly wrong. The National Institute of Arthritis and Musculoskeletal and Skin Diseases, in guidance last reviewed in July 2023, describes three things happening in a pore: too much oil, a build-up of dead skin cells, and the growth of bacteria. A rise in androgens, the male sex hormones that both sexes produce more of during puberty, makes the oil glands enlarge and produce more oil. The mixture of oil and cells plugs the follicle and lets bacteria that already live on your skin grow there, which is what produces the inflammation you can see.

Two consequences follow. Acne is not caused by being dirty, so scrubbing harder makes it worse rather than better. And on food, NIAMS is careful: chocolate and greasy food do not cause acne, though they may make it worse, and research on diet is still going on. Acne is most common in teenagers and young adults, and a doctor has real treatments for it when over-the-counter products are not enough.

Bottom line: Most of what changes during puberty is driven by hormones, not by anything you did or failed to do. What you control is the routine you build around it.

Common misconceptions

• "Everyone else has started, so something is wrong with me." The normal start window is five years wide on both timetables. Being the last in your year group to start is inside the range, and so is being the first.
• "Irregular periods in the first year or two mean something is wrong." ACOG says it may take 6 years or more after periods begin for a cycle to become regular.
• "Acne is caused by dirty skin and chocolate." NIAMS points to oil production, dead skin cells and bacteria in the pore, driven by a rise in androgens. Chocolate does not cause acne, though it may make it worse.
• "Boys and girls go through the same thing at the same time." Boys start about a year later on average and their growth peak comes about two years into puberty rather than one.
• "A period means something is wrong or injured." Bleeding is the planned shedding of a lining the body built and then did not need.

What you now know

Puberty typically starts between 8 and 13 in girls and between 9 and 14 in boys, and a doctor is worth asking if it starts before 8 or 9 or has not started by 13 or 14. The changes arrive in order: breast development, then body hair, then the growth spurt, then periods on one pathway; testicles and penis, then body hair, then muscle growth, deeper voice and facial hair on the other. The growth spurt runs about two or three years. The menstrual cycle runs from the first day of bleeding to the first day of the next, averages about 28 days with 21 to 45 also normal, involves 2 to 7 days of bleeding, and may take 6 years or more to settle into a pattern. Heavy bleeding needing a change every 1 to 2 hours, bleeding beyond 7 days, dizziness, or cycles outside 21 to 45 days are all worth a doctor's time. Acne comes from oil, dead skin cells and bacteria in a pore, driven by androgens, and washing harder is not the fix.

Sources

1. Eunice Kennedy Shriver National Institute of Child Health and Human Development. (2021). Puberty: Condition information. NICHD, National Institutes of Health. nichd.nih.gov
2. American College of Obstetricians and Gynecologists. (2022, June; reviewed 2025, November). Your first period. ACOG FAQ. acog.org
3. National Library of Medicine. (2024). Puberty. MedlinePlus. medlineplus.gov
4. National Institute of Arthritis and Musculoskeletal and Skin Diseases. (2023, July). Acne. NIAMS, National Institutes of Health. niams.nih.gov
5. American Academy of Pediatrics. (2014, December 19). Physical development of school-age children. HealthyChildren.org. healthychildren.org

One person with measles can pass the infection to as many as 18 other people. That figure comes from the World Health Organization measles fact sheet dated 15 July 2026, and it is worth sitting with, because most illnesses do not behave like that. A single case in a school with low vaccination is not one case for long.

This lesson is about the chain that number describes: what germs are, how they travel, what your body does about them, and what washing your hands and being vaccinated actually change. Almost none of it is willpower. Most of it is plumbing and timing.

Four kinds of germ, and why the difference matters

Germs are microorganisms, meaning living things too small to see without a microscope. MedlinePlus, the National Library of Medicine's public health library, lists the main types as bacteria, viruses, fungi and parasites. Most of the germs in and on you cause no harm at all, and some are useful. A small minority cause infectious disease.

The split that matters most in this lesson is between bacteria and viruses. A bacterium is a single living cell that can eat, grow and divide on its own. A virus is not a cell at all. It is a package of genetic instructions in a coat, and it can only make copies of itself by getting inside one of your cells and using that cell's machinery. This is not a technicality. It is the entire reason antibiotics work on one and not the other, which is the last section of this lesson.

How a germ gets from a door handle into you

MedlinePlus lists the routes. Touching someone who has the germ, or close contact such as sharing a cup or eating utensils. Breathing air after an infected person coughs or sneezes. Touching a surface or object that has germs on it and then touching your eyes, nose or mouth. Contaminated food, water or soil. Insect and animal bites.

Notice how many of those routes end with the same five words: then touching your eyes, nose or mouth. Your hands are rarely the place an infection begins. They are the delivery vehicle. A germ on a door handle is going nowhere until a hand carries it to a face, and people touch their own faces constantly without noticing.

Key idea: Handwashing does not clean your hands for their own sake. It breaks the last step of a chain, the one between a surface and your face.

Twenty seconds, and the five steps

The CDC procedure, in guidance last reviewed on 16 February 2024, has five steps and one number.

1. Wet your hands with clean running water, warm or cold, turn off the tap and apply soap.
2. Lather, and cover the backs of your hands, between your fingers and under your nails. Those three places are where hurried washing fails.
3. Scrub for at least 20 seconds.
4. Rinse well under running water.
5. Dry with a clean towel or an air dryer.

Twenty seconds feels much longer than you expect at a sink, which is why the advice comes with a timing trick attached: hum a tune you know the length of. Time yourself once with a clock and you will find out whether your normal wash is closer to five seconds than twenty.

The CDC's list of key times is specific: before, during and after preparing food; before and after eating; before and after caring for someone who is sick; before and after treating a cut; after using the toilet; after blowing your nose, coughing or sneezing; after touching an animal, animal food or animal waste; and after touching rubbish.

When soap and water are not available, the CDC says to use an alcohol-based hand sanitizer containing at least 60 percent alcohol, and to check the label rather than assume. Sanitizer is the backup, not the equal: it does not remove dirt or grease, so visibly dirty hands still need a sink.

What your body already does, without being asked

Suppose a virus makes it in. Your immune system responds, and the CDC describes the response in terms of two words worth learning.

An antigen is any substance that causes the immune system to begin producing antibodies. In a real infection, the antigens are parts of the invading germ itself.

An antibody is a protein produced by white blood cells to identify and neutralise foreign substances. White blood cells are made in the bone marrow and travel throughout the body in low numbers, ready to multiply and attack microbes when something turns up.

Here is the part that explains why you feel ill for several days: building that response takes time. The cells have to find the invader, multiply, and produce antibodies that fit it. Meanwhile the germ is also multiplying. The days you spend in bed are the days that race is being run. Afterwards, the CDC says, the white blood cells stop multiplying and their numbers dwindle until only a few are left to keep watch. Those few are your memory of the infection.

What a vaccine adds

A vaccine works by imitating an infection. That is the CDC's own phrase, in guidance last reviewed on 10 August 2024. The active ingredient is an antigen: a weakened or killed bacterium or virus, or just a piece of its surface or its genetic material. It is enough to make your immune system respond and leave the watchers behind. It is not enough to give you the disease.

So the race described above still happens, but it happens in advance and against a harmless stand-in. When the real germ arrives, the response that took your body a week to build the first time is already available.

Two honest details. Immunity can take weeks to develop after vaccination, so it is possible to catch the disease if you are exposed just before or just after the shot. And some vaccines need more than one dose: the CDC notes that live vaccines typically need two, and non-live vaccines often need three or more, because protection from them fades.

The numbers attached to this

The World Health Organization states that immunization currently prevents 3.5 million to 5 million deaths every year, from diseases including diphtheria, tetanus, pertussis, influenza and measles. On measles specifically, WHO's fact sheet of 15 July 2026 estimates 95,000 measles deaths worldwide in 2024, mostly among unvaccinated or under-vaccinated children under the age of 5, and estimates that measles immunization prevented about 59 million deaths between 2000 and 2024.

Coverage is not complete. WHO reports that during 2025 about 85 percent of infants worldwide, some 110 million, received three doses of the diphtheria, tetanus and pertussis vaccine, while 13.5 million children received no vaccination at all and a further 6 million were only partly vaccinated.

Put the 18 from the opening paragraph beside those coverage numbers and you can see why measles returns to places that had stopped seeing it. Two doses of measles vaccine are recommended to ensure immunity and prevent outbreaks, and a disease that spreads that efficiently finds the gaps.

Antibiotics, and the thing they cannot do

An antibiotic is a medicine that kills bacteria or stops them multiplying. It works on strep throat, whooping cough and urinary tract infections, which are bacterial. The CDC states it in capital letters on its antibiotic use page, last reviewed on 23 September 2025: antibiotics DO NOT work on viruses. Colds, flu, most sore throats and bronchitis are viral, so antibiotics do nothing for them.

Taking them anyway is not neutral. The CDC notes that any time antibiotics are used they can cause side effects and contribute to the development of antibiotic resistance, which is bacteria becoming harder to kill with the medicines we have. Side effects include rash, dizziness, nausea and diarrhoea, and the CDC states that side effects from antibiotics are the most common cause of medication-related emergency department visits in children.

You cannot tell a bacterial infection from a viral one by how bad you feel. That is a doctor's job, using an examination and sometimes a test. If you have a high fever, trouble breathing, a sore throat that is getting worse rather than better, or you cannot keep fluids down, tell a parent or carer or the school nurse and let a doctor decide.

So what?: Washing your hands breaks the delivery route, vaccination arranges the immune response in advance, and antibiotics only apply to one of the four kinds of germ.

Common misconceptions

• "Antibiotics will clear up a bad cold faster." A cold is viral. The CDC is explicit that antibiotics do not work on viruses, and taking them brings side effects and resistance with no benefit.
• "Hand sanitizer is just as good as washing." It is the backup when there is no sink. It does not remove dirt or grease, and it needs at least 60 percent alcohol to be useful at all.
• "Vaccines give you a mild version of the disease." The antigen is a weakened or killed germ, or only a fragment of one. It is enough to trigger the immune response and not enough to cause the illness.
• "All germs are harmful." MedlinePlus is clear that many germs live in and on us without causing harm, and some help keep us healthy.
• "If a disease has disappeared, the vaccine is no longer needed." Measles generates up to 18 secondary infections per case, and 13.5 million children received no vaccination at all in 2025. Diseases return to gaps in coverage.

Pulling it together

Germs come in four main types, bacteria, viruses, fungi and parasites, and they travel by contact, by air after a cough or sneeze, by contaminated surfaces, food and water, and by bites. Most of those routes end with a hand touching a face, which is what the CDC handwashing procedure interrupts: five steps, at least 20 seconds of scrubbing, and sanitizer with at least 60 percent alcohol only when there is no sink. Your immune system answers an infection by producing antibodies, proteins made by white blood cells that identify and neutralise foreign substances, and that response takes days to build. A vaccine imitates an infection using an antigen that cannot cause the disease, so the response is ready before the germ arrives. WHO estimates immunization prevents 3.5 million to 5 million deaths a year. Antibiotics act on bacteria only, and using them against a virus buys side effects and resistance instead of a cure.

Sources

1. National Library of Medicine. (2024). Germs and hygiene. MedlinePlus. medlineplus.gov
2. Centers for Disease Control and Prevention. (2024, February 16). About handwashing. Clean Hands, CDC. cdc.gov
3. Centers for Disease Control and Prevention. (2024, August 10). Explaining how vaccines work. Vaccines and Immunizations, CDC. cdc.gov
4. World Health Organization. (2026, July 15). Measles. WHO fact sheet. who.int
5. Centers for Disease Control and Prevention. (2025, September 23). About antibiotic use. Antibiotic Prescribing and Use, CDC. cdc.gov

Your body reacts to stress by releasing hormones, and those hormones make your brain more alert, tense your muscles and increase your pulse. That is how the National Library of Medicine describes it on its stress page, reviewed on 15 May 2026, and every item on that short list is something you can feel from the inside.

Which is where the trouble usually starts. You sit down in an exam hall, your heart is going faster than it should be for someone sitting still, your hands are cold, your stomach is tight, and a reasonable person concludes that something has gone wrong with them. This lesson starts from that wrong conclusion and works out exactly where it fails.

Reading the signal backwards

The pounding heart is not a malfunction. It is the output of a system doing its job, badly matched to the situation. Faster pulse means more blood to muscles. Tense muscles mean a body ready to move. A more alert brain notices more. That set of changes is genuinely useful if the thing in front of you can be fought or run away from, and it is much less useful if the thing in front of you is a page of algebra.

The system does not know the difference. It was not designed for exams, and it does not check. So the first correction is this: the sensations are evidence the alarm went off, not evidence that you are ill or that you will fail.

The second correction is about what to do next. If you read the pounding heart as a sign of illness, the sensible response is to stop and go home. If you read it as the stress response, the sensible response is to slow your breathing, start the first question, and let the system settle. Same sensation, opposite action, and the difference is entirely in the reading.

Why this matters: Learning to name the stress response takes it from being a symptom you are frightened of to being information you can use.

Stress and anxiety are not the same word

The National Institute of Mental Health, the United States government's main research body for mental health, draws the line clearly in its fact sheet on stress and anxiety.

Both can produce the same list of symptoms, and NIMH gives it: excessive worry, uneasiness, tension, headaches or body pain, high blood pressure and loss of sleep. So you cannot tell them apart by how bad you feel. You tell them apart by whether there is something out there causing it, and by whether it stops when that thing is over.

A stressor is the thing that sets the response off. NIMH points out that a stressor can be a one-time or short-term event, or something that happens repeatedly over a long time. A single test is the first kind. A class you dread every Tuesday for a year is the second, and the second is the one that does damage.

When the alarm never switches off

Short bursts of the stress response are normal and harmless. The problem is a system that stays switched on.

MedlinePlus states that stress that continues without relief keeps the body in a heightened state and raises the risk of high blood pressure, heart disease, diabetes, obesity, depression, anxiety and skin problems, and that existing health conditions can get worse. NIMH puts it in similar terms for anxiety that does not go away: you could experience problems with sleep, or with your immune, digestive, cardiovascular and reproductive systems.

Read those carefully. Neither says stress causes heart disease in a teenager. They are statements about risk over years in a body kept on alert, which is why noticing the pattern now is worth something.

The signs, as a checklist rather than a diagnosis

MedlinePlus lists what long-running stress can look like: low energy, headaches, frequent aches and pains, an upset stomach, stiffness in the jaw or neck, forgetfulness, trouble sleeping, changes in weight, and using alcohol or drugs to relax. That last one is on the list because it is common, not because it works.

A checklist is not a diagnosis. Three items on a bad week means you had a bad week. Most of the list, most weeks, for a month, is a reason to tell somebody.

Coping that holds up

NIMH's own list, from its published fact sheet, is short and unglamorous:

• Keep a journal. Writing what happened separates the event from the feeling about it.
• Use a relaxation app, or any deliberate practice of slow breathing or meditation.
• Exercise and eat regular healthy meals. You met the activity guideline in Module 2, and this is a second reason for it.
• Stick to a regular sleep routine. Module 3 is the how.
• Avoid excess caffeine. Coffee, cola and energy drinks all push the same alert system that stress is already pushing.
• Identify and challenge your negative and unhelpful thoughts, rather than arguing with the feeling.
• Reach out to friends or family who help you cope in a positive way.

Notice what is not on the list: getting more done, being tougher, or ignoring it until it goes. Notice also that four of the seven are physical rather than mental. Sleep, food, movement and caffeine are levers on the same system, and they are levers you can reach.

Coping that costs more than it pays

Some responses feel like relief and make the week worse. Staying up to finish everything trades sleep for work and returns you to the same day with less capacity. Avoiding the thing entirely shrinks the stressor for an evening and grows it by the deadline. Scrolling until 01:00 is neither rest nor distraction, just delay with a light in your face. And using alcohol or other drugs to relax appears on the medical list of stress symptoms, not on the list of treatments.

The core of it: A coping strategy is only working if the situation is smaller afterwards, not just quieter for an hour.

Exactly how to get help

NIMH's guidance is plain: if you are struggling to cope, or the symptoms of your stress or anxiety will not go away, it may be time to talk to a professional. You do not have to reach a particular level of bad first.

In practice, for someone your age, that means telling a parent or carer, or asking your school counsellor or school nurse, who can arrange the next step. A doctor is the other route, and you can ask a parent to book an appointment without explaining everything to them first.

If you are in the United States and things are severe, including any thought of hurting yourself, call or text 988, the Suicide and Crisis Lifeline, or chat at 988lifeline.org. It answers 24 hours a day, every day, and it is free. Telling someone is not an overreaction and it is not a betrayal of yourself.

Common misconceptions

• "Stress and anxiety are the same thing." NIMH separates them: stress generally responds to an external cause, anxiety is internal and can persist when no threat is present.
• "A pounding heart before a test means something is wrong with me." It means hormones raised your pulse and alerted your brain. The system fires whether or not the threat is one you can run from.
• "All stress is bad." A short-lived stress response is normal. The health risks in the sources are attached to stress that continues without relief.
• "You should only ask for help when you cannot cope at all." NIMH sets the bar at struggling to cope or symptoms that will not go away, which is considerably earlier.

The takeaway

The stress response releases hormones that alert the brain, tense the muscles and raise the pulse, which is a real and normal reaction rather than an illness. NIMH separates stress, which answers an external cause, from anxiety, which is internal and can persist with no current threat, and notes that both produce worry, tension, headaches, raised blood pressure and lost sleep. A stressor can be a single event or something repeated over a long time, and it is the long-running kind that carries risk: stress without relief is linked to high blood pressure, heart disease, diabetes, obesity, depression and anxiety. The coping list that current guidance supports is journalling, relaxation practice, exercise and regular meals, a steady sleep routine, less caffeine, challenging unhelpful thoughts, and reaching out to people who help. If you are struggling to cope or symptoms will not go away, that is already the point at which NIMH says talk to a professional, and 988 answers at any hour.

Sources

1. National Institute of Mental Health. (2020). I'm so stressed out! Fact sheet (NIH Publication No. 20-MH-8125). National Institutes of Health. nimh.nih.gov
2. Berger, F. K. (reviewer). (2026, May 15). Stress and your health. MedlinePlus Medical Encyclopedia, National Library of Medicine. medlineplus.gov
3. National Institute of Mental Health. (2025). Caring for your mental health. NIMH, National Institutes of Health. nimh.nih.gov
4. 988 Suicide and Crisis Lifeline. (2026). Get help. Substance Abuse and Mental Health Services Administration. 988lifeline.org

In 2021, an estimated 5.0 million adolescents aged 12 to 17 in the United States had at least one major depressive episode. That is 20.1 percent of everyone that age, and it comes from the National Survey on Drug Use and Health as reported by the National Institute of Mental Health. One in five.

Hold that number next to the way people talk about depression, which is usually as something rare, dramatic, and happening to somebody else. It is not rare. In a class of thirty, the arithmetic says several people. This lesson is about what these conditions actually are, what treatment is, and the exact sentences that start it.

How common is common

The third row is the one to stare at. Most adolescents who had a major depressive episode did not get treatment for it that year. Not because treatment does not exist. That gap is made of not recognising it, not saying it, and not knowing who to say it to, which are the three things this lesson can actually change.

A word on the fourth row: those anxiety figures come from a survey run between 2001 and 2004, which is old, and they measure whether a person has ever had an anxiety disorder rather than whether they have one now. Say the year beside the number and you have told the truth about it.

Sadness is not depression, and worry is not an anxiety disorder

Everybody feels low. Everybody worries. Neither is a disorder, and treating ordinary feelings as illnesses is its own kind of harm. The difference is not how bad the feeling is on its worst afternoon. It is duration and interference.

That two-part test, weeks or months plus interference, is NIMH's own threshold for when a young person should be seen by a professional. It is deliberately not a test of how much you are suffering, because people are terrible judges of that in their own case.

In short: Duration and interference, not intensity, are what separate a bad stretch from something to get looked at.

What depression looks like at your age

Depression is not permanent sadness. NIMH's guide for teenagers, published in 2022, describes feeling sad, anxious, worthless or empty most of the time for a few weeks or longer, and lists the things that come with it: losing interest in activities you used to enjoy, irritability, pulling away from friends, school work sliding, eating or sleeping much more or much less than usual, tiredness that rest does not fix, trouble remembering and concentrating, and thoughts of suicide.

Two of those deserve a note. Irritability is on the list because in young people depression very often shows as being snappish and angry rather than tearful, which is why it gets read as attitude. And tiredness that sleep does not fix is different from being short of sleep, which you can test against what you learned in Module 3.

What an anxiety disorder looks like

NIMH draws the line like this: an anxiety disorder involves more than occasional worry or fear. The anxiety does not go away, it is felt in many situations rather than one, and it can get worse over time. The symptoms interfere with ordinary activities such as school work and relationships.

The word covers several conditions, and NIMH names generalised anxiety disorder, panic disorder, social anxiety disorder and phobia-related disorders. Being nervous before a presentation is not social anxiety disorder. Avoiding every situation where you might have to speak, for months, and building your timetable around that avoidance, is the kind of pattern that belongs in front of a professional.

Treatable, and what that means in practice

NIMH states it plainly: mental illnesses can be treated, and the earlier treatment is started, the more effective it can be. For depression, the options are psychotherapy, which is talk therapy, medication, or a combination of the two.

Talk therapy is not being told to cheer up. It is structured work with a trained person on what you think, what you do, and what to change, usually weekly, usually for a set number of sessions. Medication is prescribed and monitored by a doctor, is not instant, and is not compulsory. Which route is right is a decision made with a clinician, not from a webpage, and not from this course.

Bottom line: These are conditions with treatments, the way asthma is. Delay is the main thing that makes them worse.

The script

Knowing you should tell someone and knowing what to say are different problems. The second one is solvable, so here is the whole thing.

1. Choose the person. NIMH's advice to teenagers is to talk to a trusted adult: a parent or guardian, a teacher, or a school counsellor. Pick the one you would find easiest, not the one you think you are supposed to pick.
2. Choose the moment. Not in a corridor between lessons. Ask for five minutes, or send two sentences in a message if saying it out loud is too much.
3. Use a plain opening. Something like: I have been feeling low most days for about a month and it is getting in the way of school. I think I need some help with it.
4. Name the two facts that matter. How long it has been going on, and what it is stopping you doing. Those are the two things a professional will ask first.
5. Ask for a specific next step. Can we see the school counsellor, or can we book a doctor's appointment.
6. If the first person does not help, tell a second. One adult reacting badly is a fact about that adult. It is not the answer to your question.

Emergencies, and friends

If you are in the United States and you are thinking about hurting yourself, or you are frightened by your own thoughts, call or text 988, the Suicide and Crisis Lifeline, or chat at 988lifeline.org. It is free, it answers at any hour, and you do not have to be in immediate danger to use it. NIMH also lists the Disaster Distress Helpline at 1-800-985-5990.

If it is a friend: take it seriously, say you are glad they told you, and do not agree to keep it secret. That last part feels like betrayal and is not. You are not qualified to carry this alone, and neither am I, and the useful move is to bring in an adult who can act. Tell them you are going to, if you can. Then do it either way.

Common misconceptions

• "Depression means crying all the time." NIMH's list for teenagers leads with feeling sad, anxious, worthless or empty, and includes irritability and anger, which is how it often looks at your age.
• "If I just had more willpower it would stop." Depression and anxiety disorders are conditions with treatments, and NIMH says the earlier treatment starts the more effective it can be. Effort is not the missing ingredient.
• "Hardly anyone actually has this." In 2021, 20.1 percent of U.S. adolescents aged 12 to 17 had a major depressive episode, and fewer than half of them were treated for it.
• "Telling an adult will make everything worse and go on my record." The adult's job is to get you to someone who can help. Being treated is the outcome associated with getting better, which is why the 40.6 percent figure matters.
• "Feeling anxious before a test means I have an anxiety disorder." NIMH requires more than occasional worry or fear: anxiety that does not go away, is felt in many situations, and interferes with ordinary life.

Looking back

Depression and anxiety disorders are common among people your age: 20.1 percent of U.S. adolescents aged 12 to 17 had a major depressive episode in 2021, about 5.0 million people, and only 40.6 percent of them received treatment that year, while an estimated 31.9 percent of adolescents aged 13 to 18 in the NCS-A survey had had an anxiety disorder at some point. Ordinary sadness and ordinary worry are not these conditions: the test is duration and interference, signs lasting weeks or months that get in the way of home, school or friendships. Depression in teenagers shows as emptiness and irritability as often as tears, and as tiredness that sleeping does not fix. An anxiety disorder is anxiety that does not go away, appears in many situations, and can worsen over time. Both can be treated, with talk therapy, medication or both, and NIMH says the earlier treatment starts the more effective it can be. Tell a trusted adult, say how long and what it is stopping, ask for a specific next step, and use 988 if it is urgent.

Sources

1. National Institute of Mental Health. (2023). Major depression: Prevalence of major depressive episode among adolescents. NIMH Statistics, based on the 2021 National Survey on Drug Use and Health. nimh.nih.gov
2. National Institute of Mental Health. (2022). Teen depression: More than just moodiness (NIMH Identification No. OM 22-4321). National Institutes of Health. nimh.nih.gov
3. National Institute of Mental Health. (2024, December). Anxiety disorders. NIMH Health Topics. nimh.nih.gov
4. National Institute of Mental Health. (2024, March). Children and mental health: Is this just a stage? NIMH Health Topics. nimh.nih.gov
5. National Institute of Mental Health. (2022). Any anxiety disorder: Prevalence among adolescents. NIMH Statistics, based on the National Comorbidity Survey Adolescent Supplement, 2001 to 2004. nimh.nih.gov

About one in five high school students in the United States reported being bullied on school property in the past year, and more than one in six reported being bullied electronically. Those are CDC figures from the Youth Risk Behavior Survey covering 2013 to 2023, on a page last reviewed on 28 October 2024. Female students reported higher rates than male students for both.

Those numbers describe the far end of what this lesson covers. The rest of it is ordinary: who you spend time with, what happens when they want something you do not want, and what you do when you are neither the target nor the person causing it but the one standing there.

What friendship is actually doing

The CDC uses the term social connectedness for the size and quality of a person's relationships, and on a page last reviewed on 15 May 2024 it links being connected to lower risk of heart disease, stroke, dementia, depression and anxiety, better sleep and better stress management. That is not a poster slogan. It is a set of health outcomes attached to whether people have someone.

Which means friendship is not a side activity that happens after the health part of your life. It is part of it.

Three tests you can apply this week

Middle school friendships change fast, and some of that churn is normal. What is worth checking is quality rather than duration.

1. The after test. How do you feel in the twenty minutes after you leave them? Steadier, or worse about yourself? Do this over several occasions, not one bad afternoon.
2. The truth test. Can you say something they will not like, in a normal voice, without it costing you the friendship?
3. The hiding test. Are you hiding this friendship, or hiding parts of yourself inside it? Having to become somebody else to stay in is the clearest single warning sign on this page.

A friend disagreeing with you, having other friends, or being better than you at something are not warning signs. They are what people are like.

What matters here: Judge a friendship by what it does to you over weeks, not by how much you want it to be a good one.

Pressure rarely sounds like pressure

Peer pressure almost never arrives as a demand. It arrives as an assumption. Everyone is going. Just hold this. Do not be weird about it. There is usually no threat attached, which is exactly what makes it effective: there is nothing obvious to refuse.

Most of it is also silent. Nobody says anything, and you change what you do because of what you think the group expects. That version is harder to spot and just as strong.

The reason a refusal feels enormous is that you are weighing a small, real, immediate cost, looking awkward for ten seconds, against a large, invisible, later one. Your brain is not lying to you about the awkwardness. It is just pricing it wrongly.

Six refusals, ranked by how much they cost you

A good refusal is short, does not argue, and does not lecture anyone. Practise saying them out loud, because a sentence you have said before comes out much more easily than one you are inventing under pressure.

• The flat no. "No thanks." Then talk about something else. Most pressure collapses when nothing pushes back against it.
• The reason that is not up for debate. "I have training tomorrow." Facts end conversations; opinions extend them.
• The blame-shift. "My mum checks, it is not worth it." Using an adult as a shield is allowed, and most adults will agree to be one if you ask them in advance.
• The exit. "I am going to find so-and-so." Leaving is a complete answer and needs no explanation.
• The swap. "Not doing that, but I will come to the thing on Saturday." Refuse the activity, keep the person.
• The pre-arranged escape. Agree a code word or emoji with a parent or carer now, so that sending it means come and get me, no questions until later.

One honest note: these do not always work, and someone who keeps pushing after a clear no has told you something about themselves. Refusing twice to the same person is not rudeness.

Bullying has a definition, and it is narrower than people think

The CDC defines bullying as unwanted aggressive behaviour by another young person or group of young people who are not siblings or current dating partners, and it requires three things to be present together:

The CDC lists four types: physical, such as hitting, kicking or tripping; verbal, such as name-calling and teasing; relational or social, such as spreading rumours and deliberately excluding someone; and damage to property. The third one is the one people fail to name as bullying while it is happening to them.

Why the definition matters: a single argument between equals is not bullying, and calling it that helps nobody. Three months of being shut out of a group chat by people with more social power than you is, whether or not anyone has ever raised their voice.

The consequences are documented. The CDC states that bullying can result in physical injury, social and emotional distress, self-harm and even death, and that it raises the risk of depression, anxiety, sleep difficulties, lower academic achievement and dropping out of school. For those who bully others, the CDC reports increased risk of substance misuse, academic problems, and experiencing violence later in adolescence and adulthood.

Cyberbullying adds three things

The American Academy of Pediatrics describes cyberbullying as a range of harmful words and actions in the digital world: mean messages, embarrassing pictures, false stories, and organising exclusion. Three features make it different from the same behaviour in a corridor.

• It can happen anyplace, any day of the week, at any time of day. There is no walking home out of it.
• The person doing it may be anonymous, so the target can be looking around a room and guessing.
• A post can spread quickly, so one message becomes an audience of hundreds before anybody acts.

The practical response reverses those three. Screenshot everything before it is deleted, because evidence is the thing adults and platforms need. Do not reply, because a reply is fuel and becomes part of the record. Block and report through the app itself. Then tell an adult, and show them the screenshots rather than describing them.

If it is happening to you: stop, walk, talk

The AAP's guidance for children, updated on 6 November 2025, is three words in order.

1. Stop. Tell the person to stop, in a firm voice. Not a shout, not a plea. The AAP even offers a line for when it is turning physical: "I will talk to you, but I am not going to fight."
2. Walk. Walk away calmly and with confidence. You are not losing; you are removing the audience and the reaction.
3. Talk. Tell a trusted adult who can help. Once is not enough if nothing changes. Tell a second adult.

If it is not stopping, the AAP's list of people to bring in is school leaders, counsellors, teachers, coaches and your doctor. A pattern that has gone on for weeks is exactly what schools have procedures for, and they cannot start those procedures without knowing.

If you are watching: you are the variable

The person with the most freedom in a bullying incident is usually the one not involved in it. The AAP's advice to bystanders is direct: do not just watch, because that gives the bully the attention they want. Say stop. Help the other person walk away with you. Online, block or unfriend the person doing it. Get help from a trusted adult, and, in the AAP's own words, seeking help for someone who has been attacked is not tattling. And be a friend afterwards: kindness towards someone who has been bullied is on the list of things that help.

You do not have to be brave in a film-scene way. Standing next to someone and saying "come on, we are going" is the entire intervention, and it works because it takes the audience away.

Key idea: Bullying runs on an audience and on silence. A bystander can remove one of those in a sentence.

Common misconceptions

• "It is not bullying unless somebody gets hit." The CDC lists relational or social bullying, such as rumours and deliberate exclusion, alongside physical bullying, and requires a power imbalance and repetition rather than an injury.
• "Telling an adult is tattling." The AAP states directly that seeking help for someone who has been attacked is not tattling. Tattling is trying to get someone in trouble; this is trying to get someone out of it.
• "If you ignore it, it stops." Sometimes. The CDC's definition includes repetition precisely because the pattern continues, and the documented outcomes are depression, anxiety, sleep problems and dropping out.
• "Peer pressure is people telling you to do things." Most of it is an assumption nobody states aloud, or a silent read of what the group expects. That is why it needs a rehearsed answer rather than a good argument.
• "Blocking someone online means you have lost." Blocking and reporting are the steps the platform provides, and screenshots taken first are what let an adult act.

Recap

Social connection is linked by the CDC to lower risk of depression, anxiety, heart disease and stroke, so friendship belongs in a health course. Judge a friendship by how you feel afterwards, whether you can disagree safely, and whether you have to hide who you are. Peer pressure usually arrives as an assumption rather than a demand, so the defence is a short rehearsed refusal: a flat no, a fact, a blame-shift, an exit, a swap, or a pre-agreed code word home. Bullying, in the CDC definition, needs unwanted aggressive behaviour, a power imbalance, and repetition, and comes in physical, verbal, relational and property forms; about one in five U.S. high school students reported being bullied at school and more than one in six electronically. Cyberbullying adds round-the-clock reach, possible anonymity, and speed, so screenshot, do not reply, block, report, tell. If it is you: stop, walk, talk. If you are watching: say stop, take the person with you, and bring in an adult, which is not tattling.

Sources

1. Centers for Disease Control and Prevention. (2024, October 28). About bullying. Youth Violence Prevention, CDC. cdc.gov
2. American Academy of Pediatrics. (2025, November 6). Bullying: It's not ok. HealthyChildren.org. healthychildren.org
3. American Academy of Pediatrics. (2022, January 28). Cyberbullying: What parents need to know. HealthyChildren.org. healthychildren.org
4. Centers for Disease Control and Prevention. (2024, May 15). About social connectedness and health. Social Connection, CDC. cdc.gov

About 90 percent of child sexual abuse is carried out by someone known and trusted by the child or by the family. The CDC states that on its page about child sexual abuse, last reviewed on 16 May 2024. Almost everything people are taught about this subject as small children points the other way, at strangers, and the number says the picture is wrong.

This lesson is about a rule and how to apply it. It is written plainly because vague warnings are the least useful thing anybody has ever given a person your age.

One rule

Body autonomy is the idea that every person has the right to govern what happens to their own body. It is not a rule about danger. It is a rule about ownership, and it applies on an ordinary Tuesday as much as in an emergency.

The American Academy of Pediatrics, in guidance updated on 18 April 2025, treats this as the foundation of safety rather than an add-on: children and teenagers who feel in control of their bodies are less likely to fall prey to abusers, and if something does happen, they are more likely to tell a trusted adult. The rule and the reporting are the same skill.

The AAP's practical version is about permission: knowing who can look at or touch the parts of your body normally covered by a swimming costume, and under what conditions. A doctor examining you to check that you are healthy, with a parent or another adult present, is one of those conditions. That is a real exception with a reason attached, not a loophole.

Worth holding on to: Your body is yours. That is the whole rule, and every case below is just the rule applied.

Consent, in ordinary language

Consent means agreement that was actually asked for and freely given. Four things follow, and they are worth stating because people get them wrong in both directions.

• It has to be asked for. Silence is not agreement. Neither is not moving. Someone who has not said yes has not said yes.
• It has to be free. Agreement obtained by pestering, threatening, embarrassing someone in front of others, or using the fact that you are older, bigger or in charge is not consent.
• It is specific. Saying yes to one thing is not saying yes to something else. Agreeing to a hug is not agreeing to anything beyond a hug.
• It can be taken back. Yes five minutes ago is not yes now. Stop means stop at the moment it is said, not at the end of the game.

This is not only about sexual situations, and it is easier to learn on ordinary ones. Wrestling with a cousin, tickling, a hand on a shoulder, someone taking your phone, someone posting a photo of you. The same four points apply, which is why practising them on small things makes them available for large ones.

Four cases, tested against the rule

Surprises and secrets are not the same word

The AAP draws this distinction, and it is one of the most useful things on this page. Some secrets are safe to keep, such as plans for a surprise birthday party. Other secrets should always be shared with a trusted adult.

The test is simple. A surprise ends, and it ends with somebody pleased. A secret that must be kept for ever, that makes you uneasy, that an adult has told you not to tell, or that you have been told would get you or somebody else in trouble, is the second kind. Those are the ones that get told.

The AAP also notes how this usually works. Abusers frequently do not use physical force. They are more likely to use words and ideas to engage a child, and they often warn their victims not to tell anyone. The instruction not to tell is not a detail. It is the mechanism.

The point: If someone asks you to keep something about your body secret from your parents, that request is the thing to report, whatever else happened.

The size of it, and what that should tell you

The CDC reports research estimates that at least one in four girls and one in 20 boys in the United States experience child sexual abuse, noting that estimates vary across studies. Those numbers are here for one reason: if this has happened to you, you are not strange, you are not alone, and you did not cause it. The responsibility belongs entirely to the adult or older person who did it.

The CDC also documents that the effects are real and lasting, including depression, post-traumatic stress symptoms and increased risk of later harm. Effects that are real and lasting are exactly the kind that treatment exists for, which is the argument for telling somebody sooner rather than deciding to carry it.

Who to tell, and what to say

1. Pick an adult. A parent or carer, a teacher, the school counsellor or nurse, a coach, a relative, a friend's parent, a doctor. The AAP's guidance to parents is explicit that a child should be able to tell a different trusted adult if telling their own parent feels impossible.
2. Say it plainly. "Something happened and I need to tell you about it." You do not need the right words, and you do not need to have it in order first.
3. Expect to be believed. The AAP tells parents to affirm that they believe their child and to make clear that a child will not be in trouble for telling about information that should not be kept secret.
4. If the first adult does not act, tell a second. This is the single most important line in the lesson. One adult getting it wrong is a fact about that adult, and it changes nothing about whether you were right to tell.
5. Use a hotline if you need one. In the United States, the Childhelp National Child Abuse Hotline can be reached by calling or texting 800.422.4453. Counsellors are available 24 hours a day, seven days a week, and the service is confidential. If you are in immediate danger, call 911. If you are in crisis, 988 answers calls and texts at any hour.

If a friend tells you

Say you believe them. Say you are glad they told you. Do not ask for proof, do not ask for details, and do not promise to keep it to yourself, because that is a promise you cannot keep and should not make. Tell them you are going to bring in an adult, and then do it. Being the person a friend told is a serious thing to be, and the job is to pass it to someone who can act, not to handle it.

Common misconceptions

• "The danger is strangers." The CDC puts the figure at about 90 percent known and trusted by the child or family. The warning most people were given as small children points at the smaller share.
• "If I did not fight or shout, it does not count." The AAP notes that abusers frequently do not use physical force. Freezing is an extremely common reaction and says nothing about consent.
• "I will get in trouble for telling." The AAP tells parents to make explicitly clear that a child will not be in trouble for telling about information that should not be kept secret.
• "Saying yes once means yes from then on." Consent is specific to the thing and the moment, and it can be withdrawn at any point.
• "Refusing a hug is rude." Body autonomy is a right, not a matter of manners. An adult who cannot accept a handshake instead has a problem you did not create.

What to carry forward

Body autonomy means every person has the right to decide what happens to their own body, and the AAP treats it as the foundation of safety because people who feel in control of their bodies are more likely to tell someone when something is wrong. Consent must be asked for, freely given, specific to the thing agreed, and able to be withdrawn at any moment. A surprise ends happily; a secret you are told to keep for ever, especially one about your body, is the kind that gets told. About 90 percent of child sexual abuse is by someone known and trusted, abusers usually use words rather than force, and a warning not to tell is the mechanism rather than an accident. Tell an adult, say it plainly, expect to be believed, and if the first adult does not act, tell a second. Childhelp answers calls and texts on 800.422.4453 at any hour, confidentially, and none of this is ever the fault of the young person it happened to.

Sources

1. Centers for Disease Control and Prevention. (2024, May 16). About child sexual abuse. Child Abuse and Neglect Prevention, CDC. cdc.gov
2. American Academy of Pediatrics. (2025, April 18). Preventing child sexual abuse: What parents need to know. HealthyChildren.org. healthychildren.org
3. Childhelp. (2026). National Child Abuse Hotline. Childhelp. childhelphotline.org
4. Finkelhor, D., Shattuck, A., Turner, H., and Hamby, S. (2014). The lifetime prevalence of child sexual abuse and sexual assault assessed in late adolescence. Journal of Adolescent Health, 55(3), 329-333. Cited by the CDC as a source for its prevalence estimate.

In 2025, 5.2 percent of United States middle and high school students reported currently using e-cigarettes. About 2 million students, or 7.2 percent, reported using any tobacco product. Those figures come from the National Youth Tobacco Survey, released by the Food and Drug Administration alongside a peer-reviewed article in Nicotine and Tobacco Research, and the same survey shows use falling for tobacco products overall, combusted products and e-cigarettes across 2022 to 2025.

Turn the first number over. If 5.2 percent currently use e-cigarettes, then about 95 percent do not. That is the single most useful fact in this lesson, because the belief that everyone is doing it is both false and one of the strongest reasons people start.

What nicotine does to a brain still being built

Nicotine is the addictive chemical in cigarettes, most e-cigarettes and nicotine pouches. The CDC states it directly, on a page last reviewed on 31 January 2025: nicotine can harm brain development, which continues until about age 25. The regions it affects during adolescence are the ones handling attention, learning, mood and impulse control.

The timing is the whole argument. An adult who starts is exposing a finished brain to an addictive drug. Someone your age is exposing one that is still wiring the parts that will later decide how well you concentrate and how well you manage impulses.

The CDC adds a detail that contradicts how most people think addiction works: young people can start showing signs of nicotine addiction quickly, sometimes before regular or daily use begins. There is no safe window of casual use that you exit before anything happens.

And the aerosol is not water vapour. The CDC lists nicotine, cancer-causing chemicals, heavy metals such as nickel, tin and lead, volatile organic compounds, and ultrafine particles that can be inhaled deep into the lungs, plus flavourings such as diacetyl that have been linked to serious lung disease. Fewer harmful chemicals than cigarette smoke is not the same as safe, and the CDC says so.

So what?: The case against nicotine at your age is not that it is naughty. It is that the drug acts on tissue that is still being assembled, and that dependence starts earlier than people expect.

Alcohol, and a finding about the age of fifteen

The National Institute on Alcohol Abuse and Alcoholism puts the mechanism plainly: brains keep developing well into the twenties, and alcohol can alter that development, potentially affecting structure and function.

Then there is a specific research finding worth knowing: people who start drinking before the age of 15 are at higher risk of developing alcohol use disorder later in life. Not certain to. At higher risk. That is an argument about when, not only about whether.

Those come from the 2024 National Survey on Drug Use and Health, reported by NIAAA. Binge drinking has a technical definition: a pattern that brings blood alcohol concentration to 0.08 percent or higher, which for a typical adult means about five drinks for a man or four for a woman in about two hours. NIAAA notes that in young people fewer drinks produce the same blood alcohol level, only about three for girls and three to five for boys depending on age and size, because the amount of alcohol needed scales with body size.

The harms NIAAA lists are immediate as well as long-term: deaths, injuries, impaired judgement leading to risk-taking, and increased likelihood of being the victim or the perpetrator of violence. Alcohol is a factor in the deaths of people under 21 each year, including 1,392 from crashes involving an alcohol-impaired driver, 978 homicides, 644 from poisoning, falls, fire injuries and drowning, and 615 suicides. The minimum legal drinking age in the United States is 21, and zero-tolerance laws make driving after any amount of drinking illegal below that age.

Cannabis, honestly

The National Institute on Drug Abuse, updated 24 September 2024, says that adolescence is an important period of brain development and that cannabis use may influence the brain in ways that could lead to long-term harmful effects. Regular heavy use during adolescence is linked to negative effects on working memory, processing speed, verbal memory and academic functioning.

Two more facts that rarely make it into the conversation. First, dependence is real: NIDA cites estimates that 22 to 30 percent of people who use cannabis have cannabis use disorder, and using at younger ages increases the likelihood of developing it later. Second, the product has changed. Between 1995 and 2022 the average delta-9 THC concentration in illegal cannabis quadrupled, from 3.96 percent to 16.14 percent, and some dispensary products exceed 40 percent. Higher concentration correlates with greater likelihood of use progressing to a disorder, so an adult saying it was harmless in their day is describing a weaker substance.

Refusing, when it is a friend asking

Almost nobody is offered a first cigarette by a villain. It is a friend, at a party, being casual, and that is what makes the refusal awkward rather than frightening. The refusals from Lesson 11 apply directly, and three fit this situation especially well.

• The flat no with a subject change: "No thanks. Did you see what happened in the match?"
• The fact that ends the conversation: "I swim Saturday, it wrecks my breathing." A reason about you is not a judgement about them.
• The exit: hold a drink you already have, go and talk to someone else. Leaving needs no speech.

What does not work is arguing the health case on the spot. You will not win it, and winning it is not the goal. The goal is to still be at the party, not vaping.

If you are already using something and want to stop, that is a conversation with a parent, a doctor or a school counsellor, and not a moral failure. In the United States the SAMHSA National Helpline, 800-662-HELP, is free and confidential.

If a friend is in danger

Alcohol overdose, also called alcohol poisoning, happens when there is so much alcohol in the blood that the parts of the brain controlling breathing, heart rate and temperature begin to shut down. NIAAA lists the critical signs:

• Mental confusion or stupor.
• Difficulty staying conscious, or being unable to wake the person.
• Vomiting, or seizures.
• Slow breathing, fewer than 8 breaths a minute, or irregular breathing with 10 seconds or more between breaths.
• Slow heart rate, clammy skin, dulled responses such as no gag reflex.
• Extremely low body temperature, bluish skin colour or paleness.

What to do, in NIAAA's own terms. Call 911 immediately, and do not wait for the person to show every symptom, because someone who has passed out can die. Do not play doctor: cold showers, hot coffee and walking do not reverse an overdose and can make things worse. Do not leave them alone. If they are vomiting, help them lean forward. If they are unconscious or lying down, roll them onto one side with an ear toward the ground so they cannot choke on vomit. Be ready to tell the responders what and how much they drank, and anything else they took.

One more thing, and it is the reason this section exists. Blood alcohol keeps rising even after someone stops drinking or passes out, because alcohol already in the stomach continues to enter the blood. Letting them sleep it off is the decision that kills people. Getting a friend into trouble is survivable. The other outcome is not.

Remember: Call 911, stay, and roll them onto their side. Those three actions are the whole of what a bystander your age is expected to do.

Common misconceptions

• "Everyone vapes." In the 2025 National Youth Tobacco Survey, 5.2 percent of middle and high school students reported current e-cigarette use, and use has been falling since 2022. About 19 in 20 do not.
• "Vaping is just water vapour." The CDC lists nicotine, cancer-causing chemicals, heavy metals including nickel, tin and lead, volatile organic compounds and ultrafine particles in the aerosol.
• "You have to use a lot before you can get hooked." The CDC states that signs of nicotine addiction can appear quickly in young people, sometimes before regular daily use begins.
• "Cannabis is the same thing it was in my parents' day." Average delta-9 THC in illegal products rose from 3.96 percent in 1995 to 16.14 percent in 2022, and some dispensary products are above 40 percent.
• "Let them sleep it off." Blood alcohol keeps rising after the last drink, and an unconscious person with no gag reflex can choke. NIAAA says call 911 and do not wait for every symptom.

The short version

In the 2025 National Youth Tobacco Survey, 5.2 percent of U.S. middle and high school students currently used e-cigarettes and 7.2 percent used any tobacco product, with use falling since 2022, so the belief that everyone does it is wrong. Nicotine can harm brain development, which the CDC says continues until about age 25, affecting attention, learning, mood and impulse control, and signs of addiction can appear before regular use starts. NIAAA reports that brains keep developing well into the twenties, that alcohol can alter that development, and that starting before age 15 raises the risk of alcohol use disorder later; in 2024, 13.3 percent of people aged 12 to 20 drank in the past month and 7.6 percent binge drank. NIDA links regular heavy adolescent cannabis use to worse working memory, processing speed and school performance, notes that 22 to 30 percent of people who use cannabis have cannabis use disorder, and records THC potency quadrupling between 1995 and 2022. Refuse briefly rather than arguing. And if someone shows the signs of alcohol overdose: call 911, stay with them, and roll them onto one side.

Sources

1. U.S. Food and Drug Administration. (2025). National Youth Tobacco Survey: FDA publishes peer-reviewed journal article, releases 2025 findings. Center for Tobacco Products. fda.gov
2. Centers for Disease Control and Prevention. (2025, January 31). Health effects of vaping. Smoking and Tobacco Use, CDC. cdc.gov
3. National Institute on Alcohol Abuse and Alcoholism. (2025). Underage drinking in the United States (ages 12 to 20). Alcohol Facts and Statistics, based on the 2024 National Survey on Drug Use and Health. niaaa.nih.gov
4. National Institute on Alcohol Abuse and Alcoholism. (2024). Understanding the dangers of alcohol overdose. NIAAA, National Institutes of Health. niaaa.nih.gov
5. National Institute on Drug Abuse. (2024, September 24). Cannabis (marijuana). NIDA Research Topics, National Institutes of Health. nida.nih.gov

There is an AED on a wall near you: in a sports hall, a shopping centre, a railway station, marked by a sign. The National Heart, Lung, and Blood Institute says something about those machines that most people do not expect, in guidance last updated on 6 June 2023: even untrained people can use one in an emergency.

That sentence is the shape of this whole lesson. Emergency care is mostly a short list of simple actions that anybody can do, done in the right order, before trained help arrives. Reading about them is not the same as being trained in them, and a real first aid course with a manikin is worth more than this page. But the list is short enough to learn today.

The order that does not change

Look before you move. If a road, a fire, water or an electrical source is still dangerous, walking into it turns one casualty into two, and you are no use as the second one.

Then get help coming. The MedlinePlus first aid guidance for an unconscious person, reviewed on 8 January 2025, starts with a single instruction: call, or tell someone to call, 911 or the local emergency number. Telling a specific person is better than shouting at a crowd, because a crowd assumes someone else is doing it. Point at one person and say: you, call 911.

Only then care for the person. Check airway, breathing and pulse, and keep checking. Keep them warm until medical help arrives. If breathing or pulse stops at any point, roll them onto their back and begin CPR.

The core of it: Danger, then help, then care. Anything you do out of that order costs time you do not have.

Unconscious but breathing: the recovery position

A person lying on their back who is unconscious has a problem they cannot solve: if they vomit, they cannot clear it, and the tongue can fall back across the airway. The recovery position fixes both by using gravity.

MedlinePlus describes it like this. If the person is breathing and lying on their back, and you do not think there is a spinal injury, carefully roll them toward you onto their side. Bend the top leg so both hip and knee are at right angles. Gently tilt their head back to keep the airway open. Then keep watching, because if breathing or pulse stops you roll them back and start CPR.

The bent top leg is not decoration. It is what stops the body rolling face down again while you are doing something else.

Choking

Choking means the airway is blocked by food or an object. The signs MedlinePlus gives are direct: the person cannot speak or is having a hard time breathing. Someone coughing forcefully still has an airway, and coughing is more effective than anything you can do, so let them cough.

When they cannot, the MedlinePlus entry on abdominal thrusts, reviewed on 17 February 2026, describes two actions for an adult or a child over one year, five of each, alternating.

1. Back blows. Stand behind the person. Wrap one arm around to support their upper body and lean them forward. Use the heel of your other hand to deliver a firm blow between the shoulder blades. Check whether the object has come out after each one.
2. Abdominal thrusts. Stand behind them and reach your arms around their waist. Place your fist, thumb side in, just above the navel. Grasp the fist tightly with your other hand. Make quick, upward and inward thrusts.

If repeated attempts do not free the airway, shout for help and tell someone to call 911 or the local emergency number. Do not delay that call while you keep trying.

Bleeding

The MedlinePlus entry on bleeding, reviewed on 14 October 2025, comes down to pressure. Put pressure directly on the wound with a sterile bandage, a clean cloth or even a piece of clothing. Where possible, raise the bleeding part of the body.

The list of what not to do is just as important, because every item on it is something people instinctively do:

• Do not peek at the wound to see whether the bleeding is stopping. Lifting the dressing undoes the clot you just made.
• Do not remove a dressing that becomes soaked. Put a new one on top of it.
• Do not pull out an object stuck in the body, such as a knife, a stick or a piece of glass. Removing it can cause more damage and more bleeding.
• Do not try to clean a large wound. That causes heavier bleeding.

Get emergency help if the bleeding cannot be controlled, if a tourniquet was needed, or if a serious injury caused it.

Burns

Burns are graded by depth: superficial, once called first-degree; partial-thickness, once called second-degree; and full-thickness, once called third-degree. For a minor burn, the MedlinePlus entry reviewed on 9 April 2026 gives a number most people get wrong: run cool water over the area or soak it in a cool water bath, not ice water, and keep it under water for at least 5 to 30 minutes. Then cover it with a dry sterile bandage or a clean dressing.

Do not put oil, butter, ice, cream, oil spray, medicines or any household remedy on a severe burn. Call 911 if the burn is large, about the size of a palm or bigger, if it is full-thickness, if it was caused by chemicals or electricity, if there are signs of shock or smoke was inhaled, or if you are not sure how bad it is. Not sure is a good enough reason.

What an AED actually is

Cardiac arrest is when the heart stops pumping effectively. It is fatal unless it is treated right away with CPR and a defibrillator. An automated external defibrillator, or AED, is the portable version of that second thing, and it is designed for members of the public rather than for clinicians.

You open it and it talks. It tells you where to put the pads, it analyses the heart rhythm itself, and it will only deliver a shock if the rhythm is one a shock can fix. That is why the NHLBI can say untrained people can use one: the decision is the machine's, not yours. Your jobs are to send someone for the AED, call 911, and follow the voice.

In short: Learn where the AED is in the buildings you use. Knowing the location is most of the contribution a person your age can make.

Sun

The CDC guidance, updated on 17 June 2026, is specific. In the continental United States, ultraviolet rays are strongest from 10 a.m. to 4 p.m. daylight saving time, which is 9 a.m. to 3 p.m. standard time, so seek shade in those hours. Wear long sleeves and long trousers or a skirt where you can; tightly woven fabric protects better than loose weave, and a dry shirt better than a wet one. Wear a hat with a brim all the way around, which shades the face, the ears and the back of the neck, the three places people burn. Wear sunglasses that block both UVA and UVB. Use broad-spectrum sunscreen with SPF 15 or higher before you go outside, and put it on again if you stay out more than 2 hours and after swimming, sweating or towelling off.

Water

The CDC states that more children aged 1 to 4 die from drowning than from any other cause of death, on a page last reviewed on 29 September 2025. Its recommendations are worth reading as a set rather than one at a time.

• Formal swimming lessons reduce the risk of drowning, and children who have had them still need close and constant supervision in and around water.
• Life jackets reduce the risk of drowning while boating for people of all ages. Air-filled or foam toys are not safety devices and must not be used as if they were.
• Supervision means watching, not reading or using a phone, because drowning happens quickly and quietly. It does not look like the shouting and splashing in films.
• Open water hides currents, waves, rocks, vegetation and poor visibility. Use the buddy system and swim where there is a lifeguard.
• Do not hyperventilate before swimming underwater, and do not combine alcohol with water activities.

Common misconceptions

• "Only trained people should touch an AED." The NHLBI states that even untrained people can use one in an emergency. The machine decides whether to shock.
• "Put ice on a burn." MedlinePlus says cool water, not ice water, for at least 5 to 30 minutes, and not to put ice, butter, oil or creams on a severe burn.
• "Check whether the bleeding has stopped." Do not peek. Lifting the dressing disturbs the clot, and a soaked dressing gets another one on top rather than being removed.
• "Pull the object out." An embedded object is partly plugging the wound. Removing it can cause more damage and more bleeding.
• "Drowning is loud." The CDC warns that drowning happens quickly and quietly, which is why supervision has to be actual watching.
• "Shout for somebody to call an ambulance." Point at one person and give them the instruction. A crowd assumes somebody else already has.

What to remember

Check for danger, get help coming by telling one named person to call 911, then care. An unconscious person who is breathing, with no suspected spinal injury, is rolled onto their side with the top hip and knee at right angles and the head tilted gently back. A choking adult who cannot speak or breathe gets five back blows between the shoulder blades and five abdominal thrusts with the fist just above the navel, alternating, with 911 called if it does not clear. Bleeding gets direct pressure and elevation, with no peeking, no removing a soaked dressing, and no pulling out an embedded object. A minor burn gets cool running water for at least 5 to 30 minutes and nothing else on it. An AED talks you through itself and decides for you whether to shock. Seek shade from 10 a.m. to 4 p.m., wear a brimmed hat and broad-spectrum SPF 15 or higher reapplied every 2 hours, swim where there is a lifeguard, and use a life jacket rather than a foam toy. Then go and do a real first aid class.

Sources

1. Borke, J. (reviewer). (2025, January 8). Unconsciousness: First aid. MedlinePlus Medical Encyclopedia, National Library of Medicine. medlineplus.gov
2. National Library of Medicine. (2026, February 17). Abdominal thrusts. MedlinePlus Medical Encyclopedia. medlineplus.gov
3. National Library of Medicine. (2025, October 14). Bleeding. MedlinePlus Medical Encyclopedia. medlineplus.gov
4. National Library of Medicine. (2026, April 9). Burns. MedlinePlus Medical Encyclopedia. medlineplus.gov
5. Centers for Disease Control and Prevention. (2026, June 17). Sun safety. Skin Cancer Prevention, CDC. cdc.gov
6. Centers for Disease Control and Prevention. (2025, September 29). Drowning prevention. Drowning Prevention, CDC. cdc.gov
7. National Heart, Lung, and Blood Institute. (2023, June 6). Defibrillators. National Institutes of Health. nhlbi.nih.gov

The Dietary Guidelines for Americans 2025-2030, the tenth edition, released in January 2026, asks for three servings of vegetables and two of fruit a day. The Physical Activity Guidelines for Americans, second edition, asks anyone aged 6 to 17 for 60 minutes of moderate-to-vigorous activity every day. The National Heart, Lung, and Blood Institute asks a twelve-year-old for 9 to 12 hours of sleep. You have spent fourteen lessons collecting numbers like these. This one turns them into a term.

Four goals turn up on nearly every health plan written at the start of a term: eat healthier, exercise more, sleep more, worry less. Every one of them is reasonable. Every one of them is also unmeasurable, and that is why they are usually abandoned by about week three.

Where eat healthier actually breaks

Pick a Tuesday evening in the middle of term. You want to know whether you kept the goal. Eat healthier gives you no way to answer, because there is no quantity in it, no frequency, no time, and nothing written down. So you answer from mood: you feel like it has been a mixed week, which means the goal has quietly become a feeling about yourself rather than a thing you did.

Once a goal is a feeling about yourself, two things follow. A bad day contaminates the whole week, and a good day proves nothing. Neither is information, and a plan that produces no information cannot be adjusted. It can only be kept or abandoned, and by week three most people abandon it.

Notice that the fault is not laziness. The fault is in the wording.

Why this matters: A goal you cannot check on a Tuesday evening is not a goal. It is an intention, and intentions do not survive a term.

The five parts of a goal you can check

1. What, exactly. Not healthier. Vegetables at dinner.
2. How much. A number: three servings, 60 minutes, 20 seconds, one portion.
3. How often. Daily, or five days a week, or three days a week. Say which days if it matters.
4. When in the day. A goal attached to an existing event happens far more often than one floating free: after last lesson, before dinner, when I put my phone on charge.
5. How recorded. A tick in a diary, a note on a phone, a mark on a wall calendar. If nothing is written, nothing is known.

The four goals, rebuilt

Read the right-hand column again and notice what it does not contain: any judgement about you. Each line is a thing that either happened or did not.

One thing that does not belong on a plan at your age is a weight target. Your body is in the middle of the growth described in Lesson 7, weight is supposed to change during it, and goals aimed at making it change are the route into the trouble covered in Lesson 3. If you have a genuine concern about your growth or your weight, that is a conversation with a doctor or the school nurse, not a line in a plan you wrote yourself.

Three goals, not eleven

Fifteen lessons produce a long list of things that could be improved, and the temptation is to fix all of them from Monday. Resist it for a practical reason: every goal needs the five parts above, a place in your day, and a record. Eleven of those is a second timetable, and you already have one.

Choose three. One from food or drink, one from movement or sleep, one from mind or people. Three is enough to notice and few enough to keep.

The baseline week

Before changing anything, spend one week recording what you already do. Not what you think you do.

This matters more than it sounds. People misremember their own week in both directions, and a plan built on a guess sets targets that are either trivially easy or impossible. The activity logs in Lessons 4, 6 and 9 are baseline weeks; if you did them, you already have data. If you did not, do one now, and set your targets from what you find.

A good target sits a little above your baseline. If you currently manage vegetables at dinner twice a week, aim for five, not seven. Seven is where you find out that Thursday is always takeaway night and the whole plan collapses on a technicality.

Obstacles, written in advance

You can already name the things that will derail each goal. Write them down as if-then rules, one sentence each, before the term starts. The value is that the decision is made while you are calm rather than at 22:40 while you are tired.

• If it is raining and I will not run, then I do the indoor set: push-ups, squats and a plank.
• If I have practice until 20:30, then lights out moves to 22:00 that night only, and back to 21:45 the next.
• If there are no vegetables in the house, then I have fruit and tick it anyway.
• If I miss two days in a row, then I restart the next morning rather than writing the week off.

That last one is the most useful rule on the page. Most plans do not die from a bad week. They die from the decision, after a bad week, that the plan is over.

The weekly check

Once a week, on a day you choose, spend five minutes doing exactly this: look at what you recorded, compare it with the target, and write one number for each goal. Three out of five. Four out of seven. Then write one sentence about what to change.

The comparison is between a record and a target. It is not between how you feel now and how you remember feeling. Three out of five is not a failure and it is not a success; it is information, and the honest responses to it are to keep the target, lower it, or change when in the day it happens.

The point: A plan that gets adjusted twice in twelve weeks is working. A plan that has never been adjusted is probably not being measured.

What else belongs in the plan

Not everything in a health plan is a goal. Some of it is just information you want available on a bad day, and this course has produced a specific list:

• The names of three adults you could tell something difficult, and how to reach each of them.
• 988, the Suicide and Crisis Lifeline, which takes calls and texts at any hour in the United States.
• 800.422.4453, the Childhelp National Child Abuse Hotline, confidential and always open.
• The name of your school counsellor or school nurse, and where their room is.
• Where the nearest AED is in the buildings you use most.

Write those on the same page as the goals. The day you need them is not the day to go looking.

Common misconceptions

• "A bigger goal shows more commitment." A target far above your baseline produces a collapse in week two. The target that sits slightly above what you already do is the one still running in week twelve.
• "If I miss a few days the plan has failed." Missing days is what the if-then rules are for. The restart rule is part of the plan, not an admission that it did not work.
• "I will remember how the week went." Memory of your own behaviour is unreliable in both directions, which is why the baseline week and the written record exist.
• "A health plan should include a target weight." Not at your age. Your body is growing, and weight-focused goals are the doorway to the problems described in Lesson 3. Take that question to a doctor instead.
• "More goals means more progress." Each goal needs a place in the day and a record. Three is the number most people can actually keep.

Putting it together

Vague goals fail because they cannot be checked, so they turn into feelings about yourself rather than records of what you did. A goal you can check names what exactly, how much, how often, when in the day, and how it is recorded. Take one week to record your baseline before changing anything, then set three goals, one from food or drink, one from movement or sleep, one from mind or people, each a little above the baseline rather than far above it. Write if-then rules for the obstacles you can already predict, including the rule that two missed days means restarting the next morning. Once a week, compare the record against the target, write the number, and change one thing. Keep the help numbers on the same page as the goals. And leave weight targets out of it: that is a question for a doctor, not for a plan you wrote yourself.

Sources

1. U.S. Department of Agriculture and U.S. Department of Health and Human Services. (2026, January). Dietary Guidelines for Americans, 2025-2030 (10th ed.). odphp.health.gov
2. U.S. Department of Health and Human Services. (2018). Physical Activity Guidelines for Americans (2nd ed.). odphp.health.gov
3. National Heart, Lung, and Blood Institute. (2022, March 24). How much sleep is enough? National Institutes of Health. nhlbi.nih.gov
4. National Institute of Mental Health. (2025). Caring for your mental health. NIMH, National Institutes of Health. nimh.nih.gov