Page 18 - 新思维科学学生用书4 样章

1.3 Skeletons and movement

Activity

Find out how muscles work in pairs

You will need:

something heavy to lift, such as a large book

• Look closely at the muscles in your

arm. Also look at the pictures that show

how the arm muscles work.

• Hold the weight in one hand and
slowly lift the weight up towards you.

• Put your other hand over the front on

your upper arm. Feel how the muscle

changes as you lift the weight.

• How does the muscle at the back of
your arm feel?

• Straighten your arm. Feel what happens

to the muscle at the back of your arm.

• What happens to the muscle at the

front of your arm?

Questions

1 When you pick up a heavy book, which

muscle in your arm contracts? Which muscle in

your arm relaxes? How do you know this from doing the activity?

2 How strong are your arm muscles? Think of a way to find out that
will be a fair test.

3 How can we make our muscles bigger?

4 The heart is a special muscle that is not joined to any bones. Why

do you think the heart is not joined to any bones?

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