Teacher Points/Student Points!
At the end of the day, whoever has more points gets 5 minutes. If they win, they get to put the 5 minutes towards Friday afternoon's Choice Time. If I win, I keep the 5 minutes for learning, because the fact that I have more points means we must have lost learning time that day being off-task.
Occasionally they skunk me, meaning I didn't get any points that day. When that happens, they get 10 minutes towards Choice Time. Believe me, that is very motivating! They will remind each other to follow the rules and I don't have to say a word..."Guys! We're skunking her...get in a quiet line!" (said in an intense whisper as we were lining up to go to a special, and they know I need a quiet line to travel in the hall.)
At the beginning of the year, I award points more frequently during the day as we are building routines. Later on, I honestly forget sometimes! That's the beauty of this system, though...the number of points doesn't matter. It's just whoever has more at the end of the day. It usually works out that students earn between 20-30 minutes for Choice Time. We have a rule that if they don't earn at least 15 minutes, we roll the minutes over into another week, because less than that just isn't worth it.
One other thing that I do occasionally is to allow one student to earn a student point for the entire class. As an example, we do a yoga-type program first thing in the morning called Get Ready to Learn. I have a student with ADHD who has a very hard time sitting in his chair, let alone participating in the yoga. He regularly disrupted the other students during this time. One day I noticed that he was really trying to do the movements, so after yoga I told the class that he had earned a point for the whole class because he did something that was really hard for him. The class was excited and thanked him, and he felt great!
I do still have to deal with individual students being off-task or disruptive. I don't take a teacher point for this. I use positive time-out as recommended by Responsive Classroom. Sometimes students may need to stay in a recess and complete a behavior reflection. It varies with the situation.
So, if you're looking for a simple whole-class management system, maybe give this a try!