Good system for first graders?

I'm in a student teacher aide program where I go downstairs in the last 2 hours of school to help the teacher. The teacher writes all the kids names on the boards. If they are misbehaving she adds a red, orange, or green check to the kids name. The kids can redeem themselves, but if it's a red, they have to work harder than if it was a green. If they get 3 checks they have to sit in the corner for 10 minutes. At the end of the day, if they have no checks they get a little toy. If they have one, they stay a few minutes after talking to the teacher, if they have two, they have to do something nice (like clean the floors in the room after school), and if they have three or more the parents are contacted. Do you think this is a good system? I sort of have mixed feelings on it.