1. Fill the bottle with hot water, swirl the water around to make the bottle hot, and pour it out.
2. Refill the bottle 1/4 full with hot water and place the balloon over the top.
3. Now, fill the bowl with ice water, and place the bottle in the bowl.
4. Watch as all of the air is taken from the balloon. It might even get pulled into the bottle!
This works because hot air expands and cool air contracts. So when you first place the balloon over the bottle, the air in the bottle is hot. As the air cools from the ice water, it contracts and trys to pull more air in from the outside.
