heat loss. once i pointed this out to them, they completely understood what i was saying.
use the top rack of the oven: sometimes the kids will just throw their foods onto whichever rack they feel, however, keeping the food closer to the heat source can help reduce cooking time.
use the oven light: we all fall a little guilty of this especially when baking. it is more energy efficient to take your peeks by using the over light versus opening and shutting the over door.
do you have any others to share? 