Funny Experiment Using Air Pressure


The aim of this science fair project is demonstrate to your friends the effects of air pressure using a simple experiment.

Materials required:

  1. A glass bottle.
  2. A straw.
  3. Some clay.
  4. A marshmallow.
  5. A colored pencil.


  1. Draw a face on the flat face of a marshmallow.
  2. Put it into the glass bottle.
  3. Take the clay and wrap it around the straw.
  4. Stick the straw into the bottle and adjust the clay so that it seals the opening of the bottle except for the straw.
  5. Put the bottle in front of a mirror in such a way that the face of the marshmallow with the face is facing towards the mirror.
  6. Suck on the straw to take the air out of the bottle. Observe the funny faces shown in the mirror.
  7. After a while, stop sucking on the straw and release it from your mouth. Observe the changes in the faces.

Scientific explanation:

As you suck the air out of the bottle, the air pressure inside the bottle decreases and the marshmallow expands. When you stop sucking and release the straw from your mouth, the air rushes back into the bottle and the marshmallow contracts to its original size. As it expands and contracts, you see funny faces in the mirror.