You can do your own demonstration, on a larger scale with balls you probably have scattered around your house (or that you could borrow from the phys. ed. teacher).
But, if I stack them on top of each other and drop them, the soccer ball goes flying off, reaching an altitude many times higher than when dropped by itself. The basketball doesn't bounce back much at all. Just a little, and then it rolls away.
|The soccer ball went much higher than that - my camera timing skills aren't perfect!|
This is a demonstration of conservation of energy and momentum. Nearly all of the energy the basketball had is transferred to the soccer ball - allowing the soccer ball to fly off with more energy than it started with and the basketball, left with almost nothing, just rolls away.
You can have lots of fun experimenting with different balls - golf balls, ping pong balls, super balls, playground balls, etc. What do you think would happen with 3 balls? Give it a try!