How Muscles Move Bones · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
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How Muscles Move Bones

Science · The Human Body · ages 7-9
Name ______________________   Date ____________

  1. Which word means a muscle that you choose to use, like the ones in your legs when you kick a ball?

    • Involuntary
    • Voluntary
    • Automatic

  2. You bend your elbow to lift your hand. What does your biceps do?

    • It contracts and pulls the forearm.
    • It relaxes and lets the elbow bend.
    • It lengthens and pushes the bone.

  3. The heart is a voluntary muscle that you can choose to stop.

    Circle one:   True   False

  4. Maya's stomach muscles squeeze her food along after lunch, and she never has to think about it. What kind of muscle is this?

    • Voluntary
    • Involuntary
    • It is not a muscle

  5. You actively straighten your elbow. What does your triceps do?

    • It relaxes as the biceps pushes.
    • It lengthens to push the elbow straight.
    • It contracts and pulls on the forearm.

  6. Skeletal muscles can only work when you choose to move them.

    Circle one:   True   False

  7. Tara says, 'My elbow is still, so no arm muscle can be working.' Which fact helps check her idea?

    • A muscle can pull only while it keeps getting shorter.
    • A muscle at a still joint must be fully relaxed.
    • A muscle can keep pulling while its length stays fixed.

  8. Jay says, 'Muscles straighten my elbow by pushing the bones.' Which fact corrects his explanation?

    • Muscles use a pull for bending and straightening.
    • Muscles pull to bend and push to straighten.
    • Muscles push to bend and pull to straighten.
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How Muscles Move Bones W1-mt_6N-4TqCleR-s1

  1. Voluntary · Voluntary muscles move when you decide to move them.
  2. It contracts and pulls the forearm. · The biceps contracts and pulls to help bend your elbow. The bones change position at the joint; they do not get shorter.
  3. False · Heart muscle is involuntary. It pumps blood without you choosing each beat, including while you sleep.
  4. Involuntary · Digestive muscles work automatically, without Maya choosing to move them, so they are involuntary.
  5. It contracts and pulls on the forearm. · The triceps contracts and pulls to help straighten the elbow. The biceps relaxes more during this movement.
  6. False · You can choose to use skeletal muscles, but they can also act without a choice. Shivering is one example.
  7. A muscle can keep pulling while its length stays fixed. · A muscle can contract and pull without getting shorter. It can help hold a bone still, so no visible movement does not mean no muscle activity.
  8. Muscles use a pull for bending and straightening. · Muscles move bones by pulling. A muscle on another side of a joint can pull in the other direction; muscles do not push bones.
Worksheet · LightMySky