Make a Marble Run

Play with gravity in God's nature by making as big, intricate, extravagant or long (time) ball run as possible. Start at the top of a hill or sand dune and make a track for a marble, tennis ball, basketball or whatever you have available, and see how far you can get the ball to roll, or how long you can keep it moving before coming to a stop. For the mathematicians/scientists out there, figure out how long it would run for if it were on the Moon, Jupiter or our Sun which have different gravity strengths.