Materials A small plastic container, like a medicine cup A rock A small ball, such as a golf ball or a rubber ball A ruler Glue The Method Glue the base of the plastic cup to one end of the ruler. Once it's dry, create a mini teeter-totter by leaning the center of the ruler against the rock, so the cup faces up. Put a ball in the cup and, with your child standing off to the side of the tiny seesaw, have him press on the other end of the ruler. "This will cause the other end t...
