Rocket bends his arm. Then he tries to straighten it.
"Can one muscle do both jobs?" he asks.
Raven asks, "What do you notice?"
Nova says, "Count the pullers."
A muscle can pull on a bone.
But a muscle cannot push it back.
So muscles work in pairs, like a team.
One muscle pulls to bend your arm.
The other muscle pulls to straighten it.
While one pulls, the other one relaxes.
Put one hand on top of your other arm.
Slowly bend that arm.
Do you feel a muscle get firm and bump up?
Now slowly straighten the arm.
Now a muscle on the back side gets firm.
| Sentence | True or false? |
|---|---|
| Muscles can pull and push. | ? |
| Two muscles take turns to bend and straighten. | ? |
| A relaxed muscle stretches out. | ? |
| Your arm needs only one muscle to move. | ? |
Here are new sight words.
Look at each word. Say it. Spell it.
Old: O-L-D.
Men: M-E-N.
You found the muscle teams. Nice work!
Tomorrow you will meet muscles that work all by themselves.