We did the "hot" thing too. DS was ok, and when he was little- the oven where we lived the knobs etc were all at the back of the oven, but no we have moved here they are right on the front, DS(3) knows now not to touch, but DD (1) is just starting to explore. Unfortunately she learned hot coz she climbed in behind me as i was getting a pizza out of there and she touched the door- and it hurt. And she hasnt been near it since!!! i wouldnt recommend you burn DS's hand, but i like Frangipani's idea of letting them touch it warm to help them understand.