We chose to make a Rube-Goldberg Machine to demonstrate the transfer of energy.
Step 1: A ball rolls down an inclined plane to collide with a wooden block that in turn pushes another ball into motion.
Step 2: The next ball hits a series of "dominos" that in turn pull a string that sets a small ball in motion. This next ball sends a spool into motion down another inclined plane.
Step 3: The spool knocks over a second series of dominos. These release a string that sets a swinging hammer in motion. This hammer hits another ball, sending it down an inclined plane
Step 4: The ball rolls down and falls off the plane, in the air it hits another ball. This final ball is precariously placed at the end of a tube. After the collision it falls down the tube and hits a switch.