The best system that I have seen was one where they had to "walk their dog." If the dog walked, it was a warning, a second walk they lost five minutes of playtime. We have been in school systems with the color, and pulling crayons and I can stay they were not great systems. The teacher who had the walk the dog used a "snoopy," and the kids loved it. She also had "G..(her name) bucks." If the child did not have to walk the dog they earned 2 G Bucks. At the end of the week, they spent them in her G store, where they purchased little prizes. It was a great system and fun. She had 27 kids and no behavior issues. My HG DS never responded well to the crayon system.