High School (Balloon in a Bottle)

Take a balloon and put it inside a 1 liter bottle with the opening of the balloon stretched around the bottle top. Try to blow up the balloon -- you won't get much air in. Remove the balloon from the bottle, fill it with water and seal the bottle with a cap. Puncture a small hole in the bottle near the bottom using a nail. Remove the nail, unseal the bottle and pour the water out the top of the bottle. Put the balloon back in the bottle, and try to blow it up again. Blow hard until the balloon fills most of the bottle and cover the nail hole. The balloon will stay inflated as long as you keep the nail whole covered.

Middle School (Fake Lung)

Place a small balloon down inside a water bottle, and secure the opening around the edge of the bottle's opening. Cut off the bottom portion of the bottle. Tie the end of a large balloon, and cut off the bottom of the balloon. Secure the open end of the large balloon around the bottom of the bottle with a rubber band. While tightly holding the large balloon around the outside of the bottle with one hand, pull the knot on the other end of the balloon. The balloon inside the bottle should start to inflate like an air-filled lung.

Elementary (Hot Air Balloon)

Take a small plastic water bottle, and cover the opening with a balloon. The balloon should be hanging on the outside of the bottle. Stretch the balloon out before placing it over the opening. Do the same thing with a larger plastic bottle, and place both bottles in a freezer for 30 minutes. Fill a sink or large container with hot water, and place the small bottle in the water until about three-fourths of it is submerged in the water. The balloon should inflate slightly. Do the same thing with the larger bottle, and balloon should inflate even more because more hot air is used to inflate it.

Pre-K/Kindergarten (Fish Tank)

Fill a 2 liter plastic soda bottle one-fourth of the way with water, and drop blue food coloring in it. Drop a handful of fish gravel or clean sand into the bottle. Blow up two small balloons, let out most of the air and tie them at the ends. Insert the balloons into the water to float around like fish. Tightly seal the top of the bottle with a bottle cap, and let children play with their "fish tanks."