here is one tactic I've seen effective: A very qualified sensei was teaching class one time, and a couple senior students were goofing off and not paying attention. The sensei bowed to the class and calmly told everyone while looking at the senior students, to give him a call at home when they were ready to learn...then he just left. lol

Thats pretty cool of him. What I don't understand is why students get punished for not performing something correctly. My school is much like the military school mentioned in the first post, where effort is a big factor. We're only punished if we're being lazy, not if we are having trouble with something. Aren't you there to learn anyway?