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Body Lab 3-5 / Week 03 / Body Lab Day
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Week 03 · Muscles

Body Lab Day

Body Lab Day: Cardboard Arm
// The pullers that move you
⏱ about 15 min

Body Lab Day: Cardboard Arm

Rocket lays out cardboard, a rubber band and string. "Let's build an arm that bends!"

Raven holds up a paper fastener. "What do you notice? What could this be in a real arm?"

Nova hovers over the parts. "One piece is a joint," she says. "One piece is a puller. Match them."

The family gets ready to build.

  1. You have more than 600 muscles, and the brain controls them.
  2. Muscles can only pull, so they work in pairs, like the biceps and triceps.
  3. Tendons connect muscles to bones. Ligaments connect bones to bones.
  4. There are three kinds of muscle: skeletal, smooth and cardiac.
◇ BUILD A CARDBOARD ARM
A grown-up cuts two cardboard strips, each about as long as a ruler.
One strip is the upper arm. The other is the lower arm.
A grown-up pokes a hole near one end of each strip.
Join the two holes with a paper fastener. That is the elbow, a hinge joint.
Tape one end of the rubber band to the lower arm, just past the elbow.
Tape the other end of the rubber band near the top of the upper arm. That is the biceps.
Tape a string to the back of the lower arm. That is the triceps.
Pull the rubber band to bend the arm. Pull the string to straighten it.
Safety first
A grown-up does all cutting and hole poking.
Keep rubber bands pointed away from faces and eyes.
Pull gently so nothing snaps.
For a grown-up
Let your child test and change the model.
Ask: what part of a real arm does each piece stand for?
ARM MODEL CHECK
  • Read the question.
  • Tap your answer.
In the model, what does the paper fastener stand for?
What does the rubber band stand for?
Why does the model need the string too?
The tape links the rubber band to the cardboard. What body part is the tape like?
WHY THIS EXERCISETendons connect muscles to bones, like tape links band to cardboard.

Amazing engineers! Next week we meet the heart, a hard-working muscle, and follow the blood.

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