with carb heat on it won't give you full pwr to recover
Perhaps we need to remember that the recovery from the stall is made by reducing the angle of attack.......i.e. usually moving the stick forward.
Adding power is used to minimise the height loss.
Taking that in mind and the worst case scenario of a stall at low level one has to think about what actions are required after the stick is moved forward.
The most deadly stall/spin position is the old base to final turn. Usually at a height where even those that put the carb heat to cold on short final have hot air selected.
Thus the stall should be entered with the carb heat hot air on so that the student can practice all of the actions required to be completed in the worst case scenario.
Regards,
DFC