This demonstrates that air is an example of matter and it takes up space.
Things Required:
Empty plastic broad sack
Directions:
Fill the empty sack by opening the top and moving the sack through the air. Close the top by twisting the opening and holding it with your hand. Squeeze the sack with your other hand.
This Is What Happens:
The sack resists being squeezed.
Science Behind It:
The air molecules fill the sack and apply pressure to the inside. These gas molecules are pushing out more than you are pushing in. If enough pressure could be applied, the molecules would move closer together and the sack would deflate. You will not be able to apply enough pressure for this to happen.