Materials – two plastic bottles with caps

Directions

1. Get two plastic bottles with caps.  Put the caps on the bottles.
2. Place one bottle into the freezer and leave the second bottle on the counter as a control.
3. Wait approximately 5 minutes.
4. Take the bottle out of the freezer.  What has happened?
5. Remove the cap from the bottle that was in the freezer.  Watch what happens

What should happen?

When the plastic bottle was in the freezer with the cap on, the sides of the bottle collapsed. When the cap is removed, the bottle should return to its regular shape. The bottle on the counter shouldn’t have changed.

The cold in the freezer cools the air inside the bottle. As the air temperature changes, the air pressure drops and the sides of the bottle collapse.