manual

You need:
29
a plastic
bottle
a balloon
How to do it:
1) Put a rubber balloon over the top of an
empty bottle.
2) Heat the plastic bottle by running warm
water over it. The balloon will begin to
blow up. (Note: Don’t use hot water
or you may melt the plastic bottle.)
3) Don’t remove the balloon. Now run
the bottle under cold water and
the balloon will deflate.