Drop marbles on the sandpaper, making sure you drop them from the same height as in step one. Have the children observe what happens to the marbles as they land on the smooth surface. Ask them to predict what will happen when they land on the sandpaper. Set up your surfaces in the classroom. Have the children predict how the coin will move on each surface.
Flick coins several times with equal amount of force on each surface.
Measure the distance the coin travels. Explain the effects the properties of a surface may have on motion. Discuss changing the force of friction by increasing the amount of energy used to set an object in motion. Checkers, at least 7. Ask the children to predict what will happen if you hit the bottom checker in the pile.