At the beginning of the year I go over my rules and expectations for behavior. I am very clear and give lots of examples. I even have a Top Ten David Letterman-style list of behaviors that bug me, (only it's more than 10), and I give a humorous test with one correct response and the other three choices kind of silly. Then I post a chart with the students' names. I tell them any behavior that takes my attention away from teaching will result in being given a "point" on the chart. When students do misbehave I just say, "so and so, that's a point." I have found this cuts down on nagging. If a student has less than 5 points at the end of the week that student gets a small treat like a jolly rancher and a special 10 minute recess at the end of the day on Friday. If a child hurts another child, that is an automatic 5 points. With really unruly classes I have taken away the rest of the week's recesses upon reaching 5 points. I guess for a more positive angle you could give the students 5 points and take away one when students demonstrate undesirable behavior. Even annoying behavior such as forgetting to put a name on a paper can be corrected. Three times and it's a point and so on.