In Elementary School, one of my most favorite things to do during PE was to play with the huge rainbow parachute. Everyone had a color to hold and we all shook the parachute up and down to create waves. Sometimes we would throw dodge balls on top of the parachute and make try to make them "jump" out the other side of the parachute. Obviously no one really thought of this game as a physics game. Everyone would try to shake the parachute harder to make the balls go higher. In reality, the real principle of this game was wave interference.
Everyone around the parachute creates their own transverse wave by moving the parachute up and down. With everyone moving their hands at different rates, constructive and destructive interference are created. When the crests of two waves meet, massive constructive interference can propel the light dodgeball high into the air. When the crest and a trough of two different waves meet, the parachute is still and no energy is transferred to the ball. The best way to reach the highest launch for the ball is if everyone is shaking the parachute at the same time with the same, large, amplitude so when the waves interfere, the amplitude doubles.
Another game we used to play is "cat and mouse." This was when one person, known as the "cat" would crawl on top of the parachute while another person, the "mouse," would crawl underneath the parachute. The cat's objective was to find the mouse while other people were shaking the parachute. The difficulty of this game was that it was very hard to see the person under the parachute because of the waves created by the other people. From a physics perspective, reflection and diffraction are two concepts that make this game hard. When the waves of the parachute hit the mouse, they would bounce off as the same waves. It isn't like the waves would just stop, they would reflect. Also, when the waves were to hit the cat, they would just curve around them, continuing to cover the other areas of the parachute where the mouse could be. This diffraction would create other waves that would make it harder to find the mouse.
If only our Pre-School teachers knew and applied the physics of waves, they could have taught us not only the best strategy to win these games but also an interesting topic in physics!