The focus should be on stall recovery
yes and no...
spin recovery at 500ft is nearly impossible, and spin come from an asymmetric stall.
so the best way to teach your student, is 1)to avoid a stall and 2) how to recover from a stall/spin.
Kids,you need really to take the command, and simulate a low approach on long final, and show to your student that this situation is very dangerous unless you take appropriated measure like point the nose under the horizon, apply power,etc...
Simulate slow approach, Point at you speed to your student by X reference power and nose/horizon .
Ask him, what should you do if speed is too slow, maybe do a go around, no?
try to find 3-4 different scenarios why a pilot enter in this dangerous situation . 1-planes in front of you is slow 2: extend final, I am too low and too slow 3:go around with no power added,...
just focusing on stall recovery is not enough, believe me.