Projects‎ > ‎(1) Discrepant Events‎ > ‎

Air Pressure - Magic Balloon (Sabiha Dalal)


Sabiha Dalal, 6th grade Special Education Teacher at Sepulveda MS

Principle(s) Illustrated

  1. This demonstration shows the fundamental physics of air pressure. 


  • Science Standard

            8th Grade: Focus on Physical Science

            3. Structure of Matter
            e.) Students know that in solids the atoms are closely locked in position and can only
                 vibrate; in liquids the atoms and molecules are more loosley connected and can collide
                 with and move past one another; and in gases the atoms and molecules are free to move
                 independently; colliding frequently.

Questioning Script 


            1.) helium balloon (2)

            2.) 1.5 -2 liter plastic bottle (2)

            3.) pin or tack


                1.) Make a small hole at the bottom or side on one of the plastic bottles. 
                2.) Place one balloon inside the neck of each bottle and stretch the opening of the balloon over the top of the 
                     bottle, so that the opening is covered completely.
                3.) Have two volunteers blow inside each bottle. Observe what happens.

         Prior knowledge & experience:

Students are already familiar with the properties of a balloon and how to blow it up.

Root question:

1.) When I blow into the bottle with the balloon what will happen?

2.) Why does one balloon expand inside the bottle and the other balloon does not 


3.) Explain why the bottle with the hole at the bottom allows for the balloon to expand.

4.) What have you learned about air pressure from this activity?

5.) Why does the balloon inflate when you pinch the base out? 

6.) Name a part of your body that acts the same way as these two demonstrations. 

Target response: Students will learn that when there is an opening in an enclosed area such as a bottle or a cup; air can escape and allow room for something else (like the inflated balloon). This example of air pressure relates to our lungs. As we breathe air in, our lungs shrink; and as we breathe out our lungs expand. This is the same principle when your ear pops. 
Common Misconceptions:

When blowing up a balloon, we move air into a compressed space, as the balloon inflates. When the balloon is placed inside a sealed bottle, there is no way for the bottle's air to escape, so the balloon does not inflate. The pressure inside the bottle is greater than the pressure that occurs from blowing on the balloon. When there is a hole at the bottom of the bottle, the air can escape; hence the balloon inflates. 

Photographs and Movies
 bottle with no hole bottle with hole\]

Air Pressure - Magic Balloons

Put all photos in the class Picasa Album and reference here. 

Additional Resources/References
Balloon Air Pressure Magic (Instructions)

How does air pressure work? (Content information)