Chapter 1 of 8

All 8 chapters
  1. 1The skeleton, readunderstood
  2. 2Joints, readunderstood
  3. 3Muscles move bones, readunderstood
  4. 4Teeth, readunderstood
  5. 5Food groups, readunderstood
  6. 6A balanced diet, readunderstood
  7. 7Exercise and rest, readunderstood
  8. 8Keeping food safe, readunderstood

S2.3.1 Chapter 1

The skeleton

What is under my skin that holds me up?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

  • Name the skull, ribs, backbone and the main arm and leg bones
  • Explain three jobs of the skeleton: support, protect and move

Press your fingers on the top of your head. Feel the hard shape under your skin. Now press the side of your chest. You feel hard, curved bones.

All your bones together make your skeleton. An adult has 206 bones. A baby is born with about 300. Some join together as the baby grows.

Draw it first

Draw the skeleton and name its bones

  1. A standing skeleton seen from the front, drawn in three steps. First the plain skeleton. Then the names skull, ribs and spine. Then the names arm bones and leg bones. Labels: skull, ribs, spine, arm bones, leg bones.

    1 Draw a round head and a long back. Add a cage of ribs, arms and legs.

  2. A standing skeleton seen from the front, drawn in three steps. First the plain skeleton. Then the names skull, ribs and spine. Then the names arm bones and leg bones. Labels: skull, ribs, spine, arm bones, leg bones.skullribsspine

    2 Write skull, ribs and spine. Draw a line from each word to its bones.

  3. A standing skeleton seen from the front, drawn in three steps. First the plain skeleton. Then the names skull, ribs and spine. Then the names arm bones and leg bones. Labels: skull, ribs, spine, arm bones, leg bones.skullribsspineleg bonesarm bones

    3 Write arm bones and leg bones. Draw a line to each.

The skull is a hard case round your head. Your brain is soft. The skull protects it.

A slice through the head. The hard skull, drawn with hatching, is a ring round the soft brain. Labels: skull, brain.skullbrain

Your ribs are curved bones. They make a cage round your heart and lungs. They keep these soft parts safe. They move a little when you breathe.

A slice through the chest. A cage of curved ribs goes round two lungs and the heart. Labels: ribs, lungs, heart.ribslungsheart

Your backbone runs down the middle of your back. It is also called the spine. It holds you up. The nerves that carry messages run down inside it. The backbone protects them.

The backbone is not one long bone. It is a stack of small bones. This is why you can bend.

A backbone drawn twice as a stack of small bones. On the left the stack is straight. On the right the same small bones make a bent stack. Labels: backbone, small bones, straight, bent.backbonesmall bonesstraightbent
Your backbone has many small bones. Here are a few, drawn big.

Your upper arm has one bone. Your lower arm has two. Your thigh has one bone. It is the longest bone in your body. Your lower leg has two bones.

The bones of one arm. One long bone is in the upper arm, marked 1 bone. Two bones are in the lower arm, marked 2 bones. Labels: upper arm, lower arm, 1 bone, 2 bones.1 bone2 bonesupper armlower arm
The bones of one leg. One long bone is in the thigh, marked 1 bone. Two bones are in the lower leg, marked 2 bones. Labels: thigh, lower leg, 1 bone, 2 bones.1 bone2 bonesthighlower leg
The thigh bone is the longest bone in your body.

Your skeleton has three jobs. It supports you: it holds you up and gives you your shape. It protects soft parts inside you. It helps you move.

See it three ways

As a picture

A table with two columns, Job and Which bones. Row one: support, with backbone, legs. Row two: protect, with skull, ribs. Row three: move, with arm, leg bones.JobWhich bonessupportbackbone, legsprotectskull, ribsmovearm, leg bones

In words

The backbone and leg bones hold you up. The skull and ribs protect soft parts. Muscles pull on arm bones and leg bones to make you move.

In symbols

An adult has 206 bones. A baby is born with about 300.

Try it

Feel your own skeleton

You need: your own body, a friend, if you like.

Be safe: Press gently. Stop if anything hurts.

  1. Tap the top of your head with a finger. Is it hard or soft?
  2. Reach behind you. Run a finger down the middle of your back. Feel the bumps.
  3. Put your hands on the sides of your chest. Breathe in deeply. Feel the curved ribs move.
  4. Run a finger down the front of your lower leg. Feel the long hard bone close under the skin.

What you will see: Your head is hard. Your back has a row of small bumps. These are bones of the backbone. Your ribs are curved and they move as you breathe. The bone in your lower leg is long and hard.

If you cannot try it, this is what happens.
A table with two columns, Where and You feel. Row one: head, with hard and round. Row two: back, with bumps in a row. Row three: sides, with curved bones. Row four: shin, with hard and long.WhereYou feelheadhard and roundbackbumps in a rowsidescurved bonesshinhard and long

A wrong idea many people have

Bones are dead and dry, like sticks.

Why it feels right: Old bones on the ground are white and dry. A bone feels as hard as a stick.

The test that breaks it: Think of a child who breaks an arm bone. In a few weeks the bone mends and joins again. A dead stick never mends. Or mark a growing child's height on a wall. Mark it again after some months. The child is taller because the bones grew.

What is true: Bones in your body are alive. They grow, they have blood, and a broken bone mends. The dry bones on the ground are from an animal that died.

A bone mends in three pictures. First a bone is broken in two, labelled broken. Then a hatched patch joins the two parts, labelled mending. Last the bone is whole again, labelled mended. Labels: bone, broken, mending, mended.brokenbonemendingmended
A broken bone mends because the bone is alive.

Key words

skeleton
all the bones in your body.
skull
the hard bones of your head. They protect your brain.
ribs
curved bones that make a cage round your heart and lungs.
backbone
the stack of small bones down your back. It is also called the spine.

Back to your guess

The answer is B: Bones hold me up, keep soft parts safe and help me move.

Your bones make a frame called a skeleton. It holds you up, keeps soft parts safe and helps you move.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Look at the picture. Which bones make a cage round the heart and lungs?

    A standing skeleton seen from the front with three names and lines to the bones. Labels: skull, ribs, spine.skullribsspine
    Tap your answer.

    1. Not this one. The skull is the case round the brain, in the head. Try another.

    2. Yes, that is right. The ribs are curved bones. They make a cage that protects the heart and lungs.

    3. Not this one. The spine runs down the back. It is not a cage round the chest. Try another.

    See the answer

    ribs

    The ribs are curved bones. They make a cage that protects the heart and lungs.

    • If you chose A: The skull is the case round the brain, in the head.
    • If you chose C: The spine runs down the back. It is not a cage round the chest.

  2. What are the three jobs of the skeleton?

    Tap your answer.

    1. Yes, that is right. It supports you and protects soft parts. Muscles pull on bones to move you.

    2. Not this one. Bones do not do these jobs. Look at the three jobs again. Try another.

    3. Not this one. The skull and ribs protect. Muscles pull on bones to move you. Try another.

    See the answer

    It holds you up, protects soft parts and helps you move.

    It supports you and protects soft parts. Muscles pull on bones to move you.

    • If you chose B: Bones do not do these jobs. Look at the three jobs again.
    • If you chose C: The skull and ribs protect. Muscles pull on bones to move you.

  3. Why can you bend your back?

    Tap your answer.

    1. Not this one. Bones are hard. The backbone bends because it is made of many small bones. Try another.

    2. Not this one. The ribs make a cage round the chest. The bending comes from the backbone. Try another.

    3. Yes, that is right. Many small bones in a stack can bend where they meet.

    See the answer

    The backbone is a stack of small bones.

    Many small bones in a stack can bend where they meet.

    • If you chose A: Bones are hard. The backbone bends because it is made of many small bones.
    • If you chose B: The ribs make a cage round the chest. The bending comes from the backbone.

  4. Tariq says, "Bones are dead, like dry sticks." Is he right?

    Tap your answer.

    1. Not this one. Your bones grow as you grow, and a broken bone mends. Dead sticks do not. Try another.

    2. Yes, that is right. Living bones have blood in them. They grow, and they can mend when broken.

    3. Not this one. Bones are alive at every size. An adult bone mends when it breaks, too. Try another.

    See the answer

    No. Bones in the body are alive. They grow and mend.

    Living bones have blood in them. They grow, and they can mend when broken.

    • If you chose A: Your bones grow as you grow, and a broken bone mends. Dead sticks do not.
    • If you chose C: Bones are alive at every size. An adult bone mends when it breaks, too.

  5. A baby is born with about 300 bones. An adult has 206. About how many more bones does a baby have?

    See the answer

    About 94 more

    Take 206 away from 300. That gives 94. The 300 is not exact, so say about 94. Some bones join together as a baby grows.

  6. Name the bones in your leg, from the top to the ankle.

    See the answer

    One thigh bone, then two bones in the lower leg.

    The thigh bone is the longest bone in the body. The lower leg has two bones.

  7. Which sentence about your arm bones is true?

    Tap your answer.

    1. Not this one. Only the upper arm has one bone. The lower arm has two bones side by side. Try another.

    2. Not this one. It is the other way round. The upper arm has one long bone. The lower arm has two. Try another.

    3. Yes, that is right. The upper arm has one long bone. The lower arm has two bones side by side.

    See the answer

    The upper arm has one bone and the lower arm has two.

    The upper arm has one long bone. The lower arm has two bones side by side.

    • If you chose A: Only the upper arm has one bone. The lower arm has two bones side by side.
    • If you chose B: It is the other way round. The upper arm has one long bone. The lower arm has two.

  8. Sipho stands up straight. Which bones do most to hold him up?

    Tap your answer.

    1. Yes, that is right. The backbone and the leg bones carry your weight. This is the support job of the skeleton.

    2. Not this one. The skull and ribs protect soft parts. The backbone holds the skull up. Try another.

    3. Not this one. Arm bones help you move things. You can stand with your arms still. They do not hold you up. Try another.

    See the answer

    The backbone and the leg bones

    The backbone and the leg bones carry your weight. This is the support job of the skeleton.

    • If you chose B: The skull and ribs protect soft parts. The backbone holds the skull up.
    • If you chose C: Arm bones help you move things. You can stand with your arms still. They do not hold you up.

Keep it

Copy this into your exercise book.

The skeleton has three jobs. It supports you, protects soft parts and helps you move. The skull protects the brain. The ribs protect the heart and lungs. The backbone is a stack of small bones.

Draw: A skeleton. Label the skull, ribs, backbone, arm bones and leg bones.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

No internet tomorrow? Save the whole book as one file (704 KB). It opens on any phone.