Why do your biceps bulge?

Human Machine Unit

Lesson 1 of 4

Muscles & Skeleton

Lesson narration:

Activity Prep

In this lesson, students discover the mechanism by which their muscles control their bones to move their bodies. In the activity, Robot Finger, students construct a model of a human finger and observe how pulling on a string (a model for tendons) causes it to bend at the joints.

What you’ll need for students

  • Robot Finger Template printout | Print 30 copies
  • Rulers | 30 rulers
  • Scissors | 30 pairs
  • Stack of Paper
    Used as a soft surface so that students can make indented lines for easier folding.
    A notebook will also work. | 30 stacks
  • Dot Stickers
    We prefer stickers because they are easier to distribute in a classroom.
    Tape also works. | 30 stickers
  • Index Cards (3x5) | 30 cards
  • Paper Clips
    Small or medium, but not jumbo sized paper clips. | 60 clips
  • String | 45 feet

Extend this Activity and Create Robot Hands

In the Extensions, we have a fun activity where students combine four robot fingers to create a robot hand. We recommend having each group of four students assemble a hand using the robot fingers they each made.

Vocabulary Words

  1. bones: the hard parts inside many animals that help give their bodies shape
  2. skeleton: all of the bones of an animal, including humans
  3. joint: a part of the body where two bones come together and can bend
  4. muscle: a part of the body that attaches to bones and allows the body to move
  5. tendon: a part of the body that attaches muscle to bone
  6. biceps: a large muscle in the upper arm
  7. structure: the specific form and shape of something
  8. function: what something does
  9. system: a group of things that affect each other and work together as a whole
  10. model: a pretend version of something that scientists use when the real thing is too big, small, or complicated to work with
  11. observe: to pay close attention to something
  12. dissect: to take something apart to study it

Discussion & Video

The robot hand can't do everything your hand can do.

Ask your student to experiment and figure out what their fingers and hands can do that the robot fingers and hands can't. Ask them: If you wanted to make the robot hand more like your hand, what would you need to add to the robot hand? Discuss this question as a class.