Help students understand the adhesive and cohesive properties of water.
Due to the polar nature of water molecules, water molecules act as tiny magnets, constantly attracting other water molecules, or other substances. The attraction between water molecules is called cohesion.The attraction of water molecules to other substances, like soil or glass, is called adhesion. The cohesive force that occurs between water molecules is so strong that when comes in contact with another medium, such as air, the water creates a “sticky skin”, which is known as surface tension. These bonds are so strong that they can support insects, such as the water strider.
Students will work together in partners to carry out this experiment. In advance of the class period, print out or photocopy the “Attractive Forces At Work” Data Sheet, enough so there is
one data sheet per group.
-Plastic cups to hold water (small size is sufficient, e.g. punch cups), one per pair of students
-Assorted coins (pennies, nickels, dimes)
-Disposable eyedroppers, one per pair
-Copies of “Attractive Forces At Work” Data Sheet, one per pair of students
For accompanying music video, go to: