Discover air pressure like never before. With just a balloon and a bottle, this item has the “WOW” factor you have been searching for! Simply place the balloon into the opening of the bottle and stretch the mouth of the balloon over the mouth of the bottle. Blow into the balloon and, when it is fully inflated, close the bottom hole of the bottle with a stopper. The normal air pressure from outside allows the balloon to stay inflated! There is no twisting or tying required. Astonish your students even more with the strength of air pressure by filling the balloon with water before releasing the stopper! This is an excellent teaching tool for introducing pressure and discussing its applications. Comes with a Teacher's Guide and recommended for grades 5 and up.

Includes:

• Glass bottle
• 2 balloons
• Rubber stopper