What you need: You and a friend

What you do: Stand with your arms to your sides. Ask your friend to wrap his or her arms around your waist. Try to lift your arms while you count slowly to 30. When you have counted to 30, tell your partner to let go. Breathe in. You should feel and see your arms float up even though you aren't trying to lift them anymore!

What happened: Muscles only work by contracting (pulling). For 30 seconds, you contracted the muscles that raised your arms. While you pushed against your friend's arms, your muscles got used to pushing out. That is called "adapting". Your muscles kept pushing out because that had become "normal" for them to do. Your arms kept lifting even though you were not trying to lift them.

Scientists want to know how the muscles of astronauts adapt to the low gravity of space and how that could affect the astronauts when they come home to Earth.

Moving in Space What You Need: a swivel chair (a chair that turns.) Use a chair that is easy to turn and does not lean back too much. Step 1) Sit in the chair. Turn yourself around in circles using your feet. This is not very hard. Step 2) Sit with your legs crossed on the chair. Try to turn in circles again. Do not touch anything. This is much harder, right? What happened? It is hard to move the chair around. You do not have anything to push off against. In space, astronauts have this same problem. There are many handles on the walls, floors, and ceilings of the shuttle to help astronauts move around. They use these handles to pull themselves from one place to another. What can you think of to help you move your chair around?