Year 3 Science · Skeletons and muscles · Summary

Year 3 Science Skeletons and muscles: summary and key words

Part of the Year 3 Science skeletons and muscles chapter. Chapter overview · whole chapter on one page

Chapter summary

Skill	Method
Skeleton	The frame of bones inside the body of a human or an animal.
Three jobs	Support holds the body up; protection guards soft parts; movement happens when muscles pull on bones.
Protecting bones	The skull protects the brain; the ribs protect the heart and the lungs; the backbone supports the body and protects the spinal cord.
Other animals	Dogs, horses, birds and fish have bones inside their bodies; snails, slugs and jellyfish do not.
Muscles	A muscle contracts (gets shorter) to pull on a bone through a tendon, and relaxes when it gets longer again.
Muscles cannot push	A muscle can only pull, so a different muscle is needed to pull the bone back.
Joints	A hinge joint moves in one direction; a ball and socket joint moves in many directions.
Pairs	The biceps bends the elbow and the triceps straightens it. When one contracts, the other relaxes.

I can say what a skeleton is, and name its three jobs: support, protection and movement
I can name the bones that protect the brain, the heart and the lungs
I can say which animals have a skeleton inside their body, and sort animals into yes and no groups
I can explain how a muscle pulls on a bone through a tendon, and why a muscle cannot push
I can name a hinge joint and a ball and socket joint, and say how each one moves
I can explain how the biceps and the triceps work in pairs to bend and straighten the elbow

skeleton: the frame of bones inside the body of a human or an animal
bone: a hard part of the skeleton
support: a job of the skeleton: holding the body up and giving it its shape
protection: a job of the skeleton: guarding the soft parts of the body
movement: moving the body, which happens when muscles pull on bones
backbone: the bones down the middle of the back; it supports the body and protects the spinal cord
spinal cord: a thick cord of nerves that runs inside the backbone
muscle: a part of the body that contracts (gets shorter) to pull on a bone
contract: to get shorter
relax: to get longer again
tendon: a strong cord that joins a muscle to a bone
joint: a place where two bones meet
hinge joint: a joint that moves in one direction, like a door, such as the elbow or the knee
ball and socket joint: a joint that moves in many directions, such as the shoulder or the hip
biceps: the muscle at the front of the upper arm, which bends the elbow
triceps: the muscle at the back of the upper arm, which straightens the elbow