Waterproof Paper Towel

Waterproof Paper Towel

Water | 5-10 minutes

In this activity, students will learn how to dunk a paper towel underwater without getting it wet.

Materials Needed

Take turns with a few:

  • Large tubs of water

  • Glasses or plastic cups

  • Paper towels

Steps:

  1. Crumple up a paper towel and put it into the bottom of the cup.  The paper towel should still stay in the cup when the cup is turned over.

  2. Holding the cup perfectly upside down, lower it straight down into the tub of water.  If you keep it absolutely vertical, you can put the cup on the bottom of the tub without letting any water into the cup.  

  3. Lift the cup straight up without tipping it.  The paper towel should be completely dry.

  4. If your paper towel got wet, dry out the inside of the cup and try it again.  Be very careful not to tip the cup on the way down or on the way up.  If you see an air bubble, you will know you tipped the cup and allowed water into the cup.

  5. After you have successfully sent a towel to the bottom and back without getting it wet, experiment a little.  Send the cup to the bottom, but then tip it just a little and watch the air bubbles come to the surface.  Look at the paper towel when you pull it up.  It’s not quite as dry this time.

Explanation:

Air takes up space! When the cup is put underwater, the water can’t get into the cup because the air is there pushing down. With no room, the water is forced to slide around the edges of the cup instead of going inside. Therefore… dry paper towel! If the cup gets tipped, the air has away to escape and water can get in.

Real World:

When a small boat flips over in the water, there is often a small bubble of air under it just like there was in the cup. This little bit of air is enough to get some breath before swimming to the surface if you’re trapped.