watch for this
3 against 2 needs a 6-tick grid and meets once. LCM(3,2) = 6, gcd(3,2) = 1.
Ask them to predict before you play it. Almost everyone guesses the hands meet more than once. They meet exactly gcd(3, 2) = 1 time — on the very first tick, and never again inside the bar. That restlessness is the whole reason drummers practise it.
The full lesson behind this: The drum kit →