Rocket builds a tent from blankets. It sags to the floor. "It keeps falling down!" he groans.
Raven lifts one corner. "What do you notice? What is missing inside?"
Nova shines a light under the blankets. "A tent needs poles," she says. "What holds your body up?"
Rocket taps his arm. "Bones! My body has a frame too."
Your skeleton is all your bones working together.
Bones give your body its shape. They also hold you up.
An adult skeleton has 206 bones.
A baby has about 300 bones at birth.
As a baby grows, some bones grow together. This is called fusing.
Bones in your body are alive. They grow and change all the time.
Bones are very light, yet strong enough to hold up your whole body.
When a child is young, some bones are made of soft cartilage.
Slowly, the cartilage is replaced by bone, with help from calcium.
Bones finish growing when a person is about 25 years old.
| Statement | True or false? |
|---|---|
| The bones in your body are alive. | ? |
| Bones never change after you are born. | ? |
| Calcium helps cartilage turn into bone. | ? |
| Bones are heavy and weak. | ? |
Brilliant bone work! Tomorrow we peek inside a bone to see what it is made of.