Big words. What do they mean?

Mr. LabRatz has two balls. One is bigger than the other. The smaller one is a bouncy ball. "I'm going to let go of both of them at the same time. Which one will hit the floor first?"

"The big ball! The big ball!" we shout.

Much to our surprise, the two balls hit the floor at the same time. Their stored energy has become motion. BUT, which one bounced higher after hitting the floor?

"The bouncy ball!"

It had more potential energy than did the larger ball.

(The younger children, having more stored up potential energy than either ball, are now competing for a chance to see how high they can make the bouncy ball bounce.)

We assemble balsa wood airplanes powered by a long rubber band. Mr. LabRatz tells us the more we turn the propeller, the tighter the rubber band will be, the more potential energy it will have, and the further the plane will fly when we throw it into the air. Mr. LabRatz makes his plane fly across the room. Some of us don't have the patience to turn and turn and turn the propeller, and so there are more quick crash landings than long flights – not that anyone cares.

If we can make a model plane fly faster with a tightly wound rubber band, what can we do with a rocket? We won't know until we can test fly it outside on a day that isn't too windy.

Up next: under the microscope