Year 3 Science: What a skeleton is and what it does
Part of the Year 3 Science skeletons and muscles chapter. Chapter overview · whole chapter on one page
What a skeleton is and what it does
A skeleton is the frame of bones inside the body. A bone is a hard part of the skeleton. The bones are joined together to make the frame.
Humans have a skeleton. Some other animals, such as dogs, horses, birds and fish, have one too.
The skeleton has three main jobs:
- support: it holds the body up and gives it its shape;
- protection: it guards the soft parts of the body (section 6.2);
- movement: muscles pull on the bones, and the bones move the body (sections 6.4 and 6.5).
Without a skeleton, a body would have no frame. It could not stand up on its own, like the soft body in the picture.
Key ideas
- A skeleton is the frame of bones inside the body of a human or an animal.
- A bone is a hard part of the skeleton.
- The three jobs of the skeleton are support, protection and movement.
- Without a skeleton, a body could not stand up on its own.
Method. Think about the frame of bones inside a body.
- Read the definition. The frame of bones inside the body is called the skeleton.skeleton
- Name it. So the word is skeleton.skeleton
- Write the answer. skeleton
Check. A skeleton is made of bones joined together. ✓
Watch out. Do not write bone. One bone is only one part of the skeleton.
Method. Find the job that is about holding the body up.
- Read the sentence. Holding the body up and giving it its shape is the job called support.support
- Name the job. So the job is support.support
- Write the answer. support
Check. Support keeps the body standing. ✓
Method. Think about the job that guards the soft parts.
- Read the jobs. Guarding the soft parts of the body is the job called protection.protection
- Name the job. So the job is protection.protection
- Write the answer. protection
Check. The skull and the ribs are two examples of protection. ✓
Watch out
Watch out: bones are hard, but they cannot move on their own. Muscles pull on bones to make them move. So a skeleton is not the same as a muscle.
Try it at home or school (with a grown-up). With a grown-up, bend forward slowly and feel for the bumps down the middle of your back. The bumps are part of your backbone. Press gently with one finger. Do not press hard.
Exam tip
Grown-up tip. Ask: “What would your body be like if it had no bones?” Let your child explain in their own words. Accept any sensible answer that mentions standing up or holding the body up.
Exercise 6A What a skeleton is and what it does
Method. Think about the frame of bones inside a body.
- Read the definition. The frame of bones inside the body is the skeleton.skeleton
- Write the answer. skeleton
Check. The skeleton is made of bones. ✓
Method. Think about the hard parts that join to make a skeleton.
- Read the definition. A bone is a hard part of the skeleton.bone
- Write the answer. bone
Check. Bones are joined together to make the skeleton. ✓
Method. Think about the three jobs listed in this section.
- Read the list. The skeleton gives support, protection and movement.support, protection and movement
- Write the answer. support, protection and movement
Check. Each job is in the list of three. ✓
Method. Think about the job that keeps a body standing.
- Read the jobs. Support means that the skeleton holds the body up.support
- Write the answer. support
Check. A skeleton gives support. ✓
Method. Think about the job that guards the soft parts.
- Read the jobs. Protection means that the bones guard the soft parts of the body.protection
- Write the answer. protection
Check. The skull protects the brain. ✓
Method. Think about what the skeleton gives the body.
- Read the sentence. The skeleton gives the body its shape.shape
- Write the answer. shape
Check. The shape of a body comes from its skeleton. ✓
Method. Think about what the skeleton does when you stand.
- Read the sentence. The skeleton holds the body up.up
- Write the answer. up
Check. Support keeps the body standing. ✓
Method. Think about the bones in your arm.
- Read the chapter. Bones are hard parts of the skeleton.hard
- Write the answer. hard
Check. A hard frame can hold the body up. ✓
Method. Think about what makes a bone move.
- Read the chapter. Bones cannot move on their own. Muscles pull on them.muscles pull
- Write the answer. false
Check. The muscles move the bones. ✓
Method. Think about the job called support.
- Read the jobs. Support means the skeleton holds the body up, so it helps the body to stand.support
- Write the answer. true
Check. Support is one of the three jobs of the skeleton. ✓
Method. Think about the animals named in this section.
- Read the list. Dogs, horses, birds and fish have a skeleton inside the body.dog, horse, bird or fish
- Write the answer. Accept any one of: dog, horse, bird, fish.
Check. Several animals have skeletons. ✓
Method. Think about what the frame does.
- Think about the frame. A frame gives support, so the body can stand up.support
- Decide. A soft clay model with no frame would flop, so Ruby is not right.no
- Write the answer. no
Check. Without a skeleton, a body cannot stand on its own. ✓
Method. Think about what happens to a soft model with nothing inside.
- Think about the model. With no frame, the soft clay has nothing to hold it up.no frame
- Make the prediction. So the model will flop or slump over.flop or slump
- Write the answer. Accept any answer that says the model will flop or slump, because it has no frame to hold it up.
Check. A prediction can be tested with a model. ✓
Method. Think about the jobs of the skeleton.
- Think about support. A hard frame can hold the body up.hard frame
- Think about protection. Hard bones also guard the soft parts of the body.guard soft parts
- Write the answer. Accept any sentence that says hard bones make a strong frame that can hold the body up and protect the soft parts.
Check. Hard bones do two jobs: support and protection. ✓