Delayed copy-cats(the important parts of the idea)

Develop the idea of a vibration travelling as the basis.

copying an action after a delay

Being a copy-cat is easy: you just do what someone else does. You can build the idea of a wave on this mimicry.

Copy what’s happening over there but after a delay. Vibrations have frequency and amplitude. Copy both.

You can alter the delay before you copy. That’s essential to the idea of a wave.