Balloon in a Bottle

Materials Needed:

Small soda bottle
Balloon
Bowl
Cold water
Hot water (This should be handled by an adult.)

What to Do:

Pour about one inch of hot water into the soda bottle.
Place the balloon hanging down into the bottle and wrap balloon mouth opening over the lip of the bottle.
Place the bottle into the bowl of cold water and watch the balloon expand inside the bottle.
Explain to the children that the hot water heats the air inside the bottle. When the bottle is put into the cold water, the air becomes cool, which creates a vacuum that pulls on the balloon and causes it to become inflated.