- One muscle pull your arm up
- The other muscle pull your arm down
- Muscles work in pairs
- One relax's while the other contracts
- Muscles can't push only pull
It was fun making the elbow.
It was hard getting it to work.
It was challenging to make the cartilidge so it wouldn't come out.
It was hard getting it to work.
It was challenging to make the cartilidge so it wouldn't come out.