I do teach them both . . . I just find that no matter how hard I try, most of my athletes want to start the clean from the ground with their back rather than their legs.
When I coached on an Olympic weightlifting team I used to carry a broomstick around. If athlete's didn't do the pullt right I'd give them a tap on the butt / low back in their starting position to remind them to stay tight in the lumbar extensors and push the legs through the floor. If they did it wrong again the tap got a little heavier.
ELITETRACK Founder