Equipment:
- Paper towel;
- glass;
- bowl of water.
Method: Place a roll of paper towel in a long glass. Turn upside down and place open end into water. Air pocket within the paper towel does not allow paper towel to get wet. Talk about displacement of air.
Background Knowledge: Make sure the paper towel in reasonably tight within the glass. As the water moves upwards as a result of adhesion (the nature of water molecules to stick together and to stick to the sides of glass and to stick to molecules of paper), the water level rises above the open end of the glass and starts to compress air within the glass. There is a point when it increases in air pressure so much as to then compress no more. It then stops. Only if there was a hole in the base of the glass for air to escape can the water level rise up higher and soak the remainder of the paper towel.
Removing the towel paper shows that some of it still remains dry.