Chapter 1: Why You Move

Chapter Introduction

Stand up.

Coach Move is serious. Before you read another word, get on your feet. Roll your shoulders back. Take one big breath. Walk a small circle around your chair. Sit back down.

Did anything change? Maybe your heart beat a little faster. Maybe your shoulders feel less tight. Maybe your breath feels deeper. Maybe nothing changed yet — that is fine too. The point is this: your body responded. It always does. Movement is not something your body sometimes does. It is something your body is always doing, even when you are sitting quietly. Your heart is moving right now. Your lungs are moving. Your eyes are moving across these words. Your gut is moving food along. You are made of motion.

The Lion is Coach Move. The Lion is powerful, calm, and direct. The Lion does not bounce around like a cheerleader and does not yell. The Lion teaches the way a wise older athlete teaches a younger one — by showing the science, expecting you to keep up, and trusting your body to learn what it was built to do.

This chapter has four lessons. Lesson 1 teaches what muscles and bones actually are — the living tissues that let you walk, run, jump, lift, and stand. Lesson 2 teaches what your heart and lungs do when you start moving harder, with specific numbers you can put on a calculator. Lesson 3 explains why every animal on Earth moves — and what happens to a body that is not asked to. Lesson 4 is the math: how many steps per day, how many minutes per week of moderate activity, and how to plan it on paper.

The Lion does not believe in punishing exercise. The Lion does not measure your worth by how strong, fast, or coordinated you are right now. Coach Move teaches one idea above all others: movement is how your body asks for what it needs. Once you understand it, you will move differently for the rest of your life.

Begin. The Lion is patient. The Lion is also unmoved by excuses. Stand up again when you finish the chapter.

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Lesson 1.1: What Your Body Is Made For

Learning Objectives

By the end of this lesson, you will be able to:

• Describe the musculoskeletal system as the system of bones, muscles, joints, and connective tissue that makes movement possible
• Identify the rough number of bones (about 206) and skeletal muscles (about 600) in the human body
• Explain how a muscle pulls on a bone to create movement
• Recognize that bone is living, growing tissue — not a fixed scaffold
• Use Wolff's Law to explain why physical activity during your tween and teen years builds stronger bones for life

Key Terms

What's Inside the Hood

Take one finger and squeeze the back of your other hand. You can feel something hard underneath. That is a bone — one of about 206 bones in your body that form your skeleton.

Now move your finger up to your upper arm and squeeze. You can feel something thicker and softer than bone, but firmer than skin. That is a muscle — one of about 600 skeletal muscles that let you move on purpose.

Together, the skeleton and the muscles make up your musculoskeletal system. That is a long word for "the system that lets you move." It also includes:

• Tendons. Tough rope-like tissue that connects each muscle to a bone. When a muscle pulls, the tendon pulls the bone.
• Ligaments. Tough strap-like tissue that connects bone to bone and keeps your joints stable.
• Joints. The places where two bones meet — like your knee, elbow, shoulder, or wrist.
• Fascia. A web of connective tissue that wraps around muscles and runs through your whole body.

About 40-45% of your body weight is made up of these tissues [1]. That means almost half of you is built specifically for moving.

If you weigh 100 pounds, about 40-45 pounds of you is muscle, bone, and connective tissue. That is a lot of body devoted to one job: motion.

How a Muscle Moves a Bone

Here is the basic move, and it is simpler than most people think:

1. Your brain decides to do something — say, lift a glass of water.
2. A signal travels down your spinal cord and out a nerve to a muscle in your arm.
3. The muscle contracts. That means it shortens — the same way a rubber band shortens when you stop stretching it.
4. The muscle's tendon pulls on a bone.
5. The bone moves around its joint.
6. Your hand lifts the glass.

This entire chain happens in less than a second. Most of it happens without you thinking about the details. You think "lift," and the body does the work.

Inside the muscle, the contraction happens through two tiny proteins called actin and myosin. They slide past each other inside each muscle fiber, like two combs ratcheting through each other's teeth. This is called the sliding filament model of muscle contraction. The fuel for the whole process is a molecule called ATP, which your body makes from food [2]. You will learn more about ATP in Grade 7.

The big idea for now: muscles pull, they do not push. Every motion you make is one muscle (or a group of muscles) pulling on a bone. To bend your arm, your biceps pulls the bone of your forearm toward your shoulder. To straighten your arm, the muscle on the back (your triceps) pulls the same bone in the opposite direction. Muscles work in pairs — when one pulls, the other relaxes.

Bones Are Alive

Most people picture bones as hard, dead things. The plastic skeleton you sometimes see in a biology classroom is dead. Your bones are not.

Bones are some of the most active tissue in your body. Two kinds of cells are constantly working in your bones:

• Osteoblasts — cells that build new bone tissue.
• Osteoclasts — cells that break down old bone tissue.

These two cell types work in a constant cycle. Old bone gets broken down. New bone gets laid down. The whole skeleton is being rebuilt cell by cell, all the time. It takes about 10 years to fully replace every bone in your body with new tissue [3].

This is one of the most important facts about your body at age 11 or 12. Bones grow stronger when you ask them to do work — when you walk, run, jump, climb, lift, and play. Bones grow weaker when they are not asked to do work — when the body mostly sits.

This rule is called Wolff's Law, named after the German doctor Julius Wolff who described it in 1892 [4]. The law is simple: bone adapts to the loads placed on it. Stress builds bone. No stress means no building.

Why This Matters Right Now

Here is the part you will not hear from most adults.

By about age 18, you will have built roughly 90% of the bone density you will have as an adult [5]. Whatever bone you have at 18 is mostly what you carry into your 30s, 50s, and 80s. Bone density slowly drops in adulthood, no matter what you do — but the starting line is set in childhood and adolescence.

Translation: the running, jumping, climbing, playing, and lifting you do between now and your late teens does not just make you feel good today. It builds the skeleton you live in for the rest of your life.

This is not a moral lecture. It is biology. A 12-year-old who walks, plays sports, carries things, and runs around regularly builds more bone density than a 12-year-old who spends most of their day sitting. The bones grow into the work you give them.

The Lion's read: this is good news. You are inside the window where the skeleton can be built. The window does not stay open forever. What you do now matters more than what you do at 25 ever will.

Lesson Check

1. About how many bones are in the adult human body? About how many skeletal muscles?
2. Name three tissues that make up the musculoskeletal system, besides bones and muscles.
3. Explain in your own words how a muscle moves a bone.
4. What is Wolff's Law?
5. About what percentage of your adult bone density is built by age 18?

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Lesson 1.2: Your Heart and Lungs in Motion

Learning Objectives

By the end of this lesson, you will be able to:

• Describe what happens to heart rate and breathing rate when you start moving
• Define resting heart rate and recall the typical range for kids ages 11-12
• Measure your own resting heart rate using your wrist or neck
• Recognize that fitter people typically have a lower resting heart rate
• Identify how your heart and lungs respond to short, moderate, and intense activity

Key Terms

What Happens When You Start Moving

Right now, sitting in a chair, your heart is beating somewhere between 70 and 100 times per minute. Your lungs are taking about 14-22 breaths per minute. Your blood is moving oxygen and fuel to every cell in your body at a steady pace, set to match how much you are currently using [6].

Now stand up, walk fast across the room, climb a flight of stairs, and walk back. Sit down and check your heart rate again. (You will learn how to check it in the next section.) Your heart is now beating faster — maybe 110-140 bpm. Your breathing is faster too. Your face might feel a little warm.

That is your cardiovascular system responding to a higher demand. Your muscles need more oxygen and more fuel to do work. Your heart is pumping more blood per minute to deliver it.

How much more? A lot. At rest, your heart pumps about 5 liters of blood per minute — roughly the volume of a 1-gallon milk jug plus a little extra. During hard activity, that number can climb to 20 liters per minute in a fit teen [7]. The same heart, four times the output. Your body is built to scale up that dramatically.

When you stop moving and rest, the system slowly returns to baseline. The faster you can drop back to your resting heart rate after activity, the better trained your cardiovascular system is. This is called heart rate recovery, and you will learn more about it in Grade 7 and Grade 8.

How to Measure Your Resting Heart Rate

This is one of the most useful skills any 6th grader can learn. It takes 60 seconds.

Method 1 — Wrist (radial pulse).

1. Hold your left hand palm-up.
2. Place the first two fingers of your right hand on the inside of your left wrist, on the thumb side, just below the bony bump.
3. Press gently until you feel a steady tap.
4. Count the taps for 60 seconds. That is your heart rate in beats per minute (bpm).

Method 2 — Neck (carotid pulse).

1. Place the first two fingers of one hand on the side of your neck, just below the angle of your jaw.
2. Press gently — not too hard — until you feel a steady tap.
3. Count the taps for 60 seconds.

For resting heart rate, take the measurement when you have been sitting still for at least 5 minutes and you are not stressed, hungry, or just done with something active. The most accurate measurement is taken in the morning, just after you wake up, before you get out of bed.

Typical resting heart rates for ages 11-12 fall in the 70-100 bpm range. Trained athletes often have lower rates — sometimes 50-60 bpm. Adults at rest run a little slower than kids on average — about 60-80 bpm.

A lower resting heart rate usually means a stronger heart. The same amount of blood gets moved with fewer beats. Training the heart over months and years lowers the resting rate, often by 10-20 bpm.

How Your Lungs Respond

Your lungs work hand in hand with your heart.

At rest, you take in about 14-22 breaths per minute. Each breath moves roughly half a liter of air in and out. Your total air movement at rest is about 5-10 liters per minute [8].

During hard activity, breathing rate climbs to 30-50 breaths per minute, each breath gets deeper, and total air movement can reach 80-100 liters per minute in a fit teen — 8 to 16 times resting volume.

Why? Because your muscles are burning much more oxygen than they were at rest. The faster you move, the more oxygen they need. The lungs scale up to deliver it.

There is a feeling that often comes with hard activity: that "out of breath" feeling. It is normal. It means your demand has temporarily outpaced supply. Your breathing keeps up, but you feel the gap. As you recover at the end of activity, your breathing stays elevated for a few minutes to "pay back" the oxygen debt and clear waste products. That's normal too.

The Lion's read: getting out of breath sometimes is not a sign that something is wrong. It is a sign that you are pushing your body into a higher gear. That is exactly what your body was built to do.

Three Levels of Activity

Researchers usually break activity into three rough levels based on heart rate and breathing.

Light activity. Walking slowly, doing light chores, easy yoga. Your heart rate is up a little (maybe 90-110 bpm for a 12-year-old). Breathing is slightly faster but still easy. You can talk in full sentences.

Moderate activity. Brisk walking, biking on flat ground, swimming a few laps, active play, gym class. Your heart rate is clearly elevated (maybe 110-140 bpm for a 12-year-old). Breathing is harder. You can still talk, but in shorter sentences.

Vigorous activity. Running, hard biking, fast swimming, soccer at game pace, basketball, hard dance, climbing. Your heart rate is high (140-180 bpm for a 12-year-old). Breathing is much harder. Talking in full sentences becomes difficult.

For a 12-year-old, all three levels are useful. The most-recommended target for kids ages 6-13 is at least 60 minutes of moderate or vigorous activity per day, recommended by the U.S. Centers for Disease Control and the World Health Organization [9, 10]. You will run the math on this in Lesson 4.

Lesson Check

1. What is a typical resting heart rate for an 11- or 12-year-old? Show the range.
2. About how much more blood per minute does the heart pump during hard activity compared to rest?
3. Describe how to measure your own pulse at the wrist.
4. Why does a lower resting heart rate usually mean a stronger heart?
5. Name the three levels of activity researchers use, and give one example of each.

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Lesson 1.3: Every Animal Moves

Learning Objectives

By the end of this lesson, you will be able to:

• Recognize that movement is universal in the animal kingdom — not unique to humans or athletes
• Identify several body systems that benefit from regular movement (musculoskeletal, cardiovascular, brain, blood sugar, mood, immune)
• Describe what happens to a human body that is not asked to move regularly
• Distinguish between movement (anything that involves muscle activation) and exercise (planned training)
• Recognize that both kinds matter for health

Key Terms

Every Animal You Have Ever Heard Of Moves

Look at any animal. Cats stalk and pounce. Dogs run. Horses gallop. Birds fly. Fish swim. Octopuses crawl across coral reefs and through tiny holes. Even animals that seem still — a sloth, a turtle, a starfish — are slowly moving, hour after hour, doing what their bodies were built to do.

This is not a coincidence. Animals evolved bodies because of movement. Without the need to find food, escape predators, find mates, and explore territory, there would be no muscles, no joints, no heart, no lungs. Movement is the reason animal bodies exist in the form they do.

Humans are no different. We did not evolve to sit. Our ancestors walked, ran, climbed, lifted, threw, and carried things across long days. Anthropologists who have studied modern hunter-gatherer groups (the closest living models of how our ancestors lived) consistently find that adults walk 5-10 miles per day and are moderately active for 3-5 hours per day [11]. They are not "exercising." They are just living.

Now compare a typical American 12-year-old's day:

• 7-8 hours of sitting in school
• 1-2 hours of homework (mostly sitting)
• 2-4 hours of screens at home (mostly sitting)
• 6-9 hours of sleeping
• A small amount of walking between places and during meals

If you add it up, the average American kid sits for about 10-12 hours per day when not sleeping. That is the opposite of what their bodies evolved for.

This is not anyone's fault. School, homework, screens, and cars are the world we live in. But the body does not know that. The body just responds to what it is asked to do. A body that is mostly asked to sit gets worse at moving, in measurable ways, fast [12].

What a Body That Doesn't Move Loses

When researchers compare children and teens who move more to those who move less, the differences show up across nearly every body system.

Musculoskeletal. Less active kids build less bone density, weaker muscles, and less flexible joints. (Wolff's Law — Lesson 1.)

Cardiovascular. Less active kids have higher resting heart rates, less efficient hearts, and earlier signs of stiffer blood vessels.

Insulin sensitivity. Less active kids' bodies handle blood sugar less well, which over time can raise the risk of diabetes [13].

Brain function. Less active kids tend to score lower on tests of attention, memory, and academic achievement, even when other factors are controlled. (You will study this in detail in Grade 8.)

Mood. Less active kids report more low mood, more anxiety, and less life satisfaction. The mood effect of movement is real and measurable — and it works in both directions [14].

Immune function. Moderate regular activity supports the immune system. Long stretches of inactivity weaken it.

Sleep. Active kids fall asleep faster and get more deep sleep. Inactive kids often struggle to fall asleep.

None of this is dramatic in any single day. None of it shows up after one week of sitting. The body is patient. But across months and years of low movement, the effects accumulate.

The Lion's view: this is not a list to scare you. It is a list to show you what is at stake. Your body is responsive to use. Use it, and it adapts in the directions you want. Stop using it, and it adapts in the directions you do not want.

Movement vs. Exercise — Both Count

Here is a useful distinction.

Exercise is planned training. Soccer practice. A workout at the gym. A swim lap session. A yoga class. Exercise has a structure, a goal, and a defined start and stop.

Movement is everything else. Walking to school. Carrying your backpack. Helping wash dishes. Climbing stairs. Walking the dog. Playing tag at recess. Fidgeting. Dancing in your room. Building a fort. Pacing while on the phone.

Both count. In fact, research increasingly shows that the total amount of movement across the day (called daily movement or sometimes non-exercise activity) matters as much as planned exercise for most health outcomes [15].

This is good news. You do not have to be an athlete to get the benefits of movement. A kid who walks to school, climbs the stairs at school, plays during recess, walks the dog after school, helps in the kitchen, and dances around their room while listening to music may move more across a day than a kid who does one hour of soccer practice and sits the rest of the day.

The Lion's frame: build a life with motion in it. Plan some exercise. But also walk when you can walk, carry when you can carry, climb when you can climb, play when you can play. All of it adds up. Your body counts it all.

What Movement Is Not

Coach Move is going to be direct about a few things.

Movement is not punishment. Some adults talk about exercise as something you do to "burn off" food, fix your body, or pay for sitting. That framing is wrong, and it is harmful. Your body does not work like a calculator that "earns" food through movement.

Movement is not about weight or how you look. Movement builds capability, function, and joy. Bodies are different sizes naturally, and that is healthy and normal. Movement is about what your body can do, not what it looks like.

Movement is not only for "athletes." Every human body was built to move. Every body benefits from movement. You do not need to be on a team, be fast, be coordinated, or be good at sports to get the benefits.

Movement is not all-or-nothing. A 10-minute walk counts. A 5-minute play break counts. Picking the stairs over the elevator counts. Small motions accumulate the same way small calorie counts add up.

The Lion's voice on this is clear and quiet: move because your body asks for motion. Not because you have to earn anything. Not because you have to look a certain way. Move because that is how the body works.

Lesson Check

1. Why does every animal you have ever heard of move?
2. About how many hours per day does an average American 12-year-old sit (when not sleeping)?
3. Name three body systems that suffer when a young person does not move regularly.
4. What is the difference between movement and exercise? Which one counts?
5. Why does the Lion say "movement is not punishment"?

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Lesson 1.4: Doing the Math — Your Movement Week on Paper

Learning Objectives

By the end of this lesson, you will be able to:

• State the research-based daily movement recommendation for ages 6-13 (at least 60 minutes of moderate-to-vigorous activity per day)
• Calculate weekly minutes of activity from a written log
• Estimate how movement adds up over a school year
• Plan one realistic week on paper to hit or exceed the recommendation
• Recognize that small daily motions add up to large weekly and yearly totals

Key Terms

What the Research Says

The U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) both recommend that children and adolescents ages 6-13 get at least 60 minutes of moderate-to-vigorous physical activity every day [9, 10]. The WHO recommendation also includes muscle- and bone-strengthening activity at least 3 days per week, which can be inside the 60 minutes (climbing, jumping, lifting, sports).

A few things to notice about that target:

• Every day, not just on practice days. Not "150 minutes per week." Sixty minutes every day. Daily.
• Moderate-to-vigorous, not light. A slow walk does not fully count. Brisk walking, biking, swimming, running, sports, dancing — those count. Light yoga or slow chores count less.
• Can be broken up. Twenty minutes here, 15 minutes there, 25 minutes after school — it all counts toward the daily 60.
• More is better, up to a point. Most kids who exceed 60 minutes per day get additional benefits.

The data on this target is strong. Studies consistently link daily 60+ minute activity to better cardiovascular health, stronger bones, better mood, better focus, better sleep, and better academic performance in school-age children [13, 14]. The 60-minute number is not a magic line — it is the research-supported floor for a healthy growing body.

How Most 12-Year-Olds Compare

Here is the hard part of the math.

A 2014 review of activity data from American children and adolescents found that on average, only about 25-30% of kids ages 6-15 hit the 60-minute target on a typical day [16]. The other 70-75% fall short, often by a lot.

This is not a moral problem. It is a math problem. School schedules are sit-heavy. Homework is sit-heavy. Most screen time is sit-heavy. The structure of a normal American kid's day does not naturally include 60 minutes of moderate activity. You have to put it in on purpose.

The good news: you do not have to be an athlete or join a team to hit the target. A few daily habits stacked together do the job:

• Walk to school (10-15 minutes each way = 20-30 minutes)
• Active recess (15-20 minutes of running, tag, basketball, etc.)
• One sport or play block after school (30-45 minutes 3-5 days/week)
• Active chores or play at home (10-20 minutes most days)

That stack alone often gets a kid into the 60-90 minute range on most days. The Lion does not require organized sports for any of it. The Lion requires motion.

Doing the Math — One Week

Let's work an example. Meet Diego. Diego is 12. He does not play a team sport this year. Here is his actual movement week, after he tracked it for 7 days.

A few things to notice.

The walking to and from school is huge. Just by walking instead of being driven, Diego gets 35 minutes of moderate activity, 5 days a week. That alone is 175 minutes — roughly 3 of the 7 daily targets, just from walking.

Recess matters. When Diego plays at recess, he hits 60-90 minutes most days. When he sits at recess (Wednesday), he falls short.

A weekend day with one big activity can carry the day. Saturday's bike ride alone hit the daily target.

The weekly total — 545 minutes — is well above the recommended floor. The 7-day target at 60 minutes/day is 420 minutes. Diego exceeded that by about 125 minutes, even without any organized sport.

If Diego added one team sport practice (say, soccer 2 days/week at 75 minutes each = 150 extra minutes), his weekly total would be near 700 minutes — about 100 minutes per day average. Strong.

Step Counts — Another Useful Number

Many phones, fitness watches, and apps count steps — each footstep counts as one. Step counts are a rough but useful way to estimate total daily movement.

For ages 6-12, research suggests a healthy target of about 11,000-13,000 steps per day for boys and 9,000-11,000 for girls [17]. Most American kids fall well below these targets.

You do not need a step-counting device to use this number. A useful rough conversion: about 1,000 steps per 10 minutes of brisk walking, so 30 minutes of walking ≈ 3,000 steps.

If a 6th grader walks 30 minutes a day, plays 20 minutes of recess (~2,500 steps), and is moderately active 30 minutes after school (~3,000 steps), they are already past 8,500 just from those three blocks. Add normal in-school walking and they often clear the recommended target without trying.

The Lion's view: step counts are a tool, not a religion. Some days you will hit them, some days you will not. Worry about the week — and worry more about consistency than perfection on any single day.

Planning Your Own Week — On Paper

Now let's design your own. Pick the next 7 days and lay out a target on paper.

Step 1 — Build the Foundation.

For each day of the week, list:

• How will you get to and from school? (Walking and biking count; driving does not.)
• What is your usual recess activity? (Active or sitting?)
• What is one block of activity after school? (Sport, play, walk, dance, anything moderate or above.)

Step 2 — Set a Target.

For each day, write your target minutes of moderate-to-vigorous activity. Aim for at least 60. If you can do 75 or 90, even better.

Step 3 — Add an Anchor.

Pick one anchor — one activity you will do every day, no matter what. Examples: a 15-minute walk after dinner; 20 jumping jacks before getting on a screen; 10 minutes of skipping rope after school. Anchors make the math much easier because you know at least that many minutes are locked in.

Step 4 — Plan the Weekend.

Weekend days often have the most flexibility. One 60-minute activity (a bike ride, a hike, a game with friends, a long swim) easily hits the daily target.

When Movement Is Hard

Coach Move is calm but honest about this. Not every day is going to be a great movement day. Some days you will be sick. Some days you will have a giant test and 4 hours of homework. Some days the weather will be bad and you cannot get outside. Some days you will just feel tired and not want to move.

That is okay. The Lion does not measure you in single days. The Lion measures you in weeks and months.

If you have stretches where movement feels impossible — your body hurts in ways that do not go away, you feel completely exhausted no matter how much you sleep, you feel low or worried for long stretches — that is worth telling a trusted adult about. A parent, a coach, a school nurse, a doctor. The Library teaches the science of healthy movement. The trusted humans around you cover the rest.

The basic rule of thumb the Lion offers: most days, move. On the days you cannot, rest. Tomorrow is another day.

Lesson Check

1. What is the daily movement recommendation for kids ages 6-13?
2. About what percentage of American kids ages 6-15 hit that target on a typical day?
3. Calculate Diego's Wednesday total from the example. Why was it lower than other days?
4. About how many steps per day is recommended for kids ages 6-12?
5. What is an anchor activity, and why does the Lion recommend having one?

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End-of-Chapter Activity: Your Movement Week on Paper

You are going to track one week of movement and design the next.

Materials

• A piece of paper or notebook
• A pencil
• A clock or phone (for timing activities)
• Optional: a step counter on a phone or watch

Procedure

Part 1 — The Audit (this coming week).

For each of the next 7 days, log every activity longer than 5 minutes that involved moderate or vigorous movement (walking, biking, sports, active play, climbing, dancing — anything that raised your heart rate and breathing noticeably). Write the activity and the minutes.

At the end of each day, total your minutes.

At the end of the week, sum your 7 daily totals to get your weekly total.

Part 2 — The Calculation.

• Did you hit 60 minutes on each day? On how many days out of 7?
• Calculate your weekly total. How does it compare to 60 × 7 = 420 minutes?
• If you maintained this weekly pattern across one school year (about 36 weeks), how many total minutes would that be?

Part 3 — The Plan (next week).

Design next week on paper. Fill in:

Aim for at least 60 minutes every day.

Part 4 — Reflection.

Write a paragraph (5-7 sentences) answering:

• What was your weekly total minutes?
• Which day was the highest? Which was the lowest?
• What is the single biggest gap between what you are doing and what you would like to be doing?
• What is one small daily change you could make starting next week?
• What is one thing you noticed about movement that you did not realize before?

Submission

Turn in:

• Your audit log (Part 1)
• Your weekly total and yearly projection (Part 2)
• Your planned week (Part 3)
• Your reflection paragraph (Part 4)

Total: about 250-350 words plus the logs.

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Vocabulary Review

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Chapter Quiz

Multiple Choice (10 questions, 2 points each)

1. About how many bones are in an adult human body?

A) 50 B) 206 C) 600 D) 2,000

2. Muscles move bones by:

A) Pushing on them B) Pulling on them through tendons C) Pumping blood D) Producing electricity

3. Wolff's Law says that:

A) Bone is a dead tissue B) Bone adapts to the loads placed on it — use builds it, sitting weakens it C) All bones grow the same way D) Bone density is set at birth

4. A typical resting heart rate for an 11- or 12-year-old falls in the range of:

A) 30-50 bpm B) 50-70 bpm C) 70-100 bpm D) 120-150 bpm

5. When you go from rest to hard activity, the total volume of blood your heart pumps per minute can rise approximately:

A) Not at all B) About 2 times C) About 4 times D) About 100 times

6. A lower resting heart rate usually means:

A) A weaker heart B) A stronger, more efficient heart C) A sign of illness D) That you ate too much

7. The CDC and WHO recommend that kids ages 6-13 get at least:

A) 15 minutes of activity per day B) 30 minutes of activity per week C) 60 minutes of moderate-to-vigorous activity per day D) 4 hours of activity per day

8. A 6th grader who walks 20 minutes to school, plays 15 minutes at recess, and walks the dog for 25 minutes after school has done approximately how many minutes of activity that day?

A) 20 B) 35 C) 60 D) 120

9. Approximately what percentage of American kids ages 6-15 hit the 60-minute daily activity target on a typical day?

A) 5% B) 25-30% C) 75% D) 99%

10. The Lion says "movement is not punishment." What does this mean?

A) Movement should be banned B) Movement is what your body asks for; it is not something you do to earn food or fix your body C) Movement is only for athletes D) Movement doesn't matter

Short Answer (5 questions, 4 points each)

11. In your own words, describe how a muscle moves a bone. Use at least three terms from this chapter (muscle, tendon, bone, joint, contraction).

12. Explain Wolff's Law and why it especially matters for an 11- or 12-year-old.

13. A friend says, "I'll start exercising when I'm older." Using two specific concepts from this chapter (bone density window, Wolff's Law, cardiovascular adaptation, etc.), write 3-4 sentences explaining why that is a poor trade.

14. A 12-year-old walks 20 minutes to school, plays 20 minutes at recess, has a 45-minute soccer practice on Tuesday and Thursday, and does an active 30-minute play block on weekends. Calculate this kid's typical weekly total movement minutes. Show your math. Did they hit the recommended weekly floor (60 × 7 = 420)?

15. Define movement and exercise in your own words. Why does the Lion say both count?

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Teacher's Guide

Pacing Recommendations

Lesson Check Answers

Lesson 1.1:

1. ~206 bones; ~600 skeletal muscles. 2. Tendons (muscle to bone), ligaments (bone to bone), joints (where bones meet), fascia (connective web). 3. The brain sends a signal through a nerve to a muscle, which contracts (shortens). The muscle's tendon pulls on a bone, and the bone moves around its joint. 4. Wolff's Law: bone adapts to the loads placed on it — use builds bone, sitting weakens it. 5. About 90%.

Lesson 1.2:

1. Typical resting heart rate for ages 11-12: 70-100 bpm. 2. About 4 times — from ~5 L/min at rest to ~20 L/min in a fit teen during hard activity. 3. Place two fingers on the inside of the opposite wrist, thumb side, just below the bony bump; press gently until you feel a steady tap; count taps for 60 seconds. 4. Because a stronger heart pumps more blood per beat, so it doesn't have to beat as many times per minute to move the same amount of blood. 5. Light (slow walk, easy yoga; talk in full sentences). Moderate (brisk walking, easy biking, active play; talk in shorter sentences). Vigorous (running, fast biking, sports at game pace; talking gets hard).

Lesson 1.3:

1. Because animals evolved bodies because of movement — finding food, escaping predators, finding mates, exploring territory. Without movement needs, animal bodies would not have evolved the way they did. 2. About 10-12 hours per day (not including sleep). 3. Any three: musculoskeletal (less bone density, weaker muscles), cardiovascular (higher resting heart rate, less efficient heart), insulin sensitivity (worse blood sugar handling), brain function (lower attention/memory scores), mood (more low mood and anxiety), immune (weaker), sleep (harder to fall asleep, less deep sleep). 4. Movement = any body motion. Exercise = planned structured training. Both count toward health. 5. Because the body does not work like a calculator that has to "earn" food or "pay" for sitting. Movement is what the body asks for; framing it as punishment is wrong and harmful.

Lesson 1.4:

1. At least 60 minutes of moderate-to-vigorous activity per day, plus muscle/bone-strengthening 3 days/week. 2. About 25-30%. 3. Wed total = 0 (sitting recess) + 35 (walking to/from school) + 10 (groceries) = 45 minutes. Lower because recess was sitting, not active play. 4. About 11,000-13,000 steps for boys; 9,000-11,000 for girls. 5. A short activity you do every day no matter what (e.g., a 15-minute post-dinner walk, 20 jumping jacks, 10 minutes of jump rope). It locks in some daily movement so the rest of the day doesn't have to do all the work.

Quiz Answer Key

Multiple Choice: 1.B 2.B 3.B 4.C 5.C 6.B 7.C 8.C 9.B 10.B

Short Answer (sample target responses):

1. The brain sends a signal down a nerve to a muscle. The muscle contracts — its protein filaments slide past each other and shorten the muscle. The muscle's tendon pulls on a bone. The bone moves around the joint. Result: motion.

2. Wolff's Law says that bone adapts to the loads placed on it — activity builds it, lack of activity weakens it. This matters most during ages 11-18 because about 90% of adult bone density is built by age 18. Whatever bone an 11- or 12-year-old builds now is mostly what they carry for the rest of their life. The window for building peak bone density does not stay open forever.

3. The window for building peak bone density mostly closes by age 18, so waiting until you are older means losing the best years for laying down strong bones (Wolff's Law). Cardiovascular fitness built in childhood and adolescence tends to carry into adulthood, while inactivity in these years often becomes an inactivity habit. Starting "when you're older" leaves the body with weaker foundations to work with.

4. Walking: 20 × 2 trips × 5 school days = 200 min. Recess: 20 × 5 = 100 min. Soccer practice: 45 × 2 = 90 min. Weekend play: 30 × 2 = 60 min. Weekly total = 200 + 100 + 90 + 60 = 450 minutes. Yes — 450 is above the 420-min weekly floor.

5. Movement is any body motion at all — walking, fidgeting, helping with chores, climbing stairs. Exercise is planned, structured training — a soccer practice, a workout, a swim class. The Lion says both count because the body responds to total daily activation, not just the planned exercise blocks. A kid who walks, climbs, and plays across the day may move more in total than a kid who does one hour of organized exercise and sits the rest of the day.

Discussion Prompts

1. Walk around the room for one minute. Take your pulse. Did your heart rate change? How much? What does that tell you?
2. The Lion says "movement is not punishment." Where have you heard adults talk about exercise in punishment terms? How is that different from what the Lion teaches?
3. About 25-30% of American kids ages 6-15 hit the 60-minute daily target. Why do you think the number is that low?
4. If your school day were redesigned to support movement, what would change?
5. The chapter says bone density is mostly set by age 18. How does that change how you think about activity at age 12?
6. Pick one of the body systems that suffers from low activity. Why is that one important to you personally?
7. What is the difference between exercise you "have to do" and movement you "want to do"? Which kind do you have more of?
8. If you tracked your movement for one week, what do you predict your weekly total would be?

Common Student Questions

• "Do I have to play a team sport?" No. The Lion does not require organized sports for health. Daily walking, recess play, active hobbies, and family activities can easily hit the 60-minute target. Team sports are great for kids who like them — and not necessary for kids who don't.
• "What if I'm not good at sports or PE?" Skill is not the point of this chapter. Capability and motion are. A kid who walks every day and plays freely is doing what the Lion is teaching, regardless of how they rank in a soccer drill.
• "Is being out of breath bad?" No — it is normal and healthy when you push your body into vigorous activity. It means your demand has briefly outpaced your supply. As long as you recover within a few minutes after stopping, it is what the body is built to do.
• "What if movement hurts?" Mild muscle soreness after a hard activity is normal. Sharp pain in joints, bones, or muscles that does not go away after a day is not — please talk to a parent or doctor. The Library teaches typical movement; pain that lingers needs trusted humans.
• "What if I really don't like exercise?" The Lion's frame: forget the word "exercise" for now. Focus on movement — walking, playing, dancing, climbing, helping carry things. Build motion into your day instead of trying to do one big block. Most kids who say they "hate exercise" find that they like moving, just not the structured-workout version.
• "What if I'm sick or injured?" Rest. Movement is for healthy days. When you are sick or injured, your body is doing different work — repair and immune function — and adding training stress slows recovery. The Lion takes rest days too.

Parent Communication Template

Dear Parents,

This week your student begins Chapter 1 of the Coach Move middle school curriculum — Why You Move. The chapter introduces the science of movement and the body's musculoskeletal and cardiovascular systems at a 6th grade reading level.

What the chapter covers:

• Basic anatomy of the musculoskeletal system (bones, muscles, tendons, ligaments, joints, fascia)
• How muscles move bones, and how bone is living, adaptive tissue (Wolff's Law)
• How the heart and lungs respond to activity, including pulse-taking and rough heart-rate ranges
• The difference between movement and exercise — and why both count
• The CDC/WHO recommendation of at least 60 minutes of moderate-to-vigorous activity per day for kids ages 6-13
• A math-based exercise estimating a personal weekly movement total

The Lion's framing is calm, capable, and direct. Movement is taught for capability, function, and joy — never for calorie burning, weight change, or body modification. The chapter explicitly rejects the framing of exercise as "punishment" or "earning" food.

A few practical notes:

• The end-of-chapter activity asks your student to track their own movement for one week and then plan the next. It is a one-time data-collection assignment, not a habit they need to maintain.
• The chapter does not require organized sports. Walking, active play, biking, and active chores can easily meet the daily 60-minute target.
• The chapter discusses pain or discomfort that lingers as a signal worth telling a trusted adult about — please talk to your healthcare provider if any of that applies.

If you have any questions, please reach out to your student's teacher.

Warmly, The CryoCove Curriculum Team

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Illustration Briefs

Lesson 1.1 — Wolff's Law Placement: After "Bones Are Alive." Scene: A side-by-side cross-section of bone. Left: a thicker, denser piece of bone with label "Active body — bone loaded with use." Right: a thinner, less dense piece labeled "Sitting body — bone not loaded." Small Coach Move (Lion) stands beside the active bone with one paw rested on it. Caption: "Wolff's Law — bone goes where you put it." Aspect ratio: 16:9 web, 4:3 print.

Lesson 1.2 — Heart and Lungs at Rest vs. Activity Placement: After "How Your Lungs Respond." Scene: Two-panel image. Left: a kid sitting, labels next to them "Heart: ~80 bpm, Breathing: ~16/min." Right: same kid running, labels "Heart: ~150 bpm, Breathing: ~40/min." Below: a small bar chart showing 5 L/min cardiac output at rest vs. 20 L/min during exercise. Coach Move (Lion) stands between the panels. Aspect ratio: 16:9 web.

Lesson 1.3 — Movement Across the Animal Kingdom Placement: After "Every Animal You Have Ever Heard Of Moves." Scene: A row of small illustrations: a running cheetah, a swimming dolphin, a climbing monkey, a flying bird, an octopus moving across rocks, a hunter-gatherer walking. Each labeled with average daily activity time. Coach Move (Lion) stands at the end of the row in a balanced upright stance. Aspect ratio: 16:9 web.

Lesson 1.4 — A Weekly Movement Stack Placement: After "How Most 12-Year-Olds Compare." Scene: A simple stacked bar chart for one week, showing minutes per day. Each bar shows colored segments: walking to school, recess, after-school play, anchor activity, weekend block. A line at 60 minutes cuts across all 7 days. Coach Move (Lion) stands at the right of the chart with a small pencil in one paw. Aspect ratio: 16:9 web.

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Citations

1. Tortora, G. J., & Derrickson, B. H. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.

2. Huxley, A. F., & Niedergerke, R. (1954). Structural changes in muscle during contraction; interference microscopy of living muscle fibres. Nature, 173(4412), 971-973.

3. Manolagas, S. C. (2000). Birth and death of bone cells: basic regulatory mechanisms and implications for the pathogenesis and treatment of osteoporosis. Endocrine Reviews, 21(2), 115-137.

4. Wolff, J. (1892). Das Gesetz der Transformation der Knochen. Hirschwald.

5. Bailey, D. A., McKay, H. A., Mirwald, R. L., Crocker, P. R., & Faulkner, R. A. (1999). A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: the University of Saskatchewan bone mineral accrual study. Journal of Bone and Mineral Research, 14(10), 1672-1679.

6. Fleming, S., Thompson, M., Stevens, R., Heneghan, C., Plüddemann, A., Maconochie, I., Tarassenko, L., & Mant, D. (2011). Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies. The Lancet, 377(9770), 1011-1018.

7. Rowland, T. W. (2008). Cardiac output and exercise hemodynamics in children. Pediatric Exercise Science, 20(4), 412-426.

8. Quanjer, P. H., Stanojevic, S., Cole, T. J., Baur, X., Hall, G. L., Culver, B. H., Enright, P. L., Hankinson, J. L., Ip, M. S. M., Zheng, J., & Stocks, J. (2012). Multi-ethnic reference values for spirometry for the 3-95-yr age range. European Respiratory Journal, 40(6), 1324-1343.

9. U.S. Department of Health and Human Services. (2018). Physical Activity Guidelines for Americans (2nd ed.). U.S. Department of Health and Human Services.

10. Bull, F. C., Al-Ansari, S. S., Biddle, S., et al. (2020). World Health Organization 2020 guidelines on physical activity and sedentary behaviour. British Journal of Sports Medicine, 54(24), 1451-1462.

11. Pontzer, H., Wood, B. M., & Raichlen, D. A. (2018). Hunter-gatherers as models in public health. Obesity Reviews, 19 Suppl 1, 24-35.

12. Tremblay, M. S., LeBlanc, A. G., Kho, M. E., Saunders, T. J., Larouche, R., Colley, R. C., Goldfield, G., & Connor Gorber, S. (2011). Systematic review of sedentary behaviour and health indicators in school-aged children and youth. International Journal of Behavioral Nutrition and Physical Activity, 8, 98.

13. Janssen, I., & LeBlanc, A. G. (2010). Systematic review of the health benefits of physical activity and fitness in school-aged children and youth. International Journal of Behavioral Nutrition and Physical Activity, 7, 40.

14. Biddle, S. J. H., & Asare, M. (2011). Physical activity and mental health in children and adolescents: a review of reviews. British Journal of Sports Medicine, 45(11), 886-895.

15. Levine, J. A. (2002). Non-exercise activity thermogenesis (NEAT). Best Practice & Research Clinical Endocrinology & Metabolism, 16(4), 679-702.

16. Belcher, B. R., Berrigan, D., Dodd, K. W., Emken, B. A., Chou, C.-P., & Spruijt-Metz, D. (2010). Physical activity in US youth: effect of race/ethnicity, age, gender, and weight status. Medicine & Science in Sports & Exercise, 42(12), 2211-2221.

17. Tudor-Locke, C., Craig, C. L., Beets, M. W., Belton, S., Cardon, G. M., Duncan, S., Hatano, Y., Lubans, D. R., Olds, T. S., Raustorp, A., Rowe, D. A., Spence, J. C., Tanaka, S., & Blair, S. N. (2011). How many steps/day are enough? For children and adolescents. International Journal of Behavioral Nutrition and Physical Activity, 8, 78.