You can "Hear Your Muscles." Do I really need to explain why
this is a cool video? Okay, I will.
Because
it addresses our goal with the “Try This Experiment Right Now” series-- which
is to teach you how to do an experiment that teaches meaningful physics with no equipment other than what you already
have in your pocket. Therefore anybody can do it.
The demos are unique, because
most teachers don’t already know about this experiment, so it improves
instruction in easy, timely yet awesome ways.