User blog comment:Secretive13/Happy December 1st!/@comment-1972973-20111202224338/@comment-3067644-20111203075240

One teacher at our school does that, blue for warning, green for second warning, yellow for a few minutes after the lesson (our day is regestration, lesson 1, break, lesson 2, lunch, lesson 3 so it always goes into our spare time), and red means detention.