I laminate these STOP signs and place a magnet on the back. They are placed on the white board. During class I can grab a stop sign and place it on the desk of an off-task student. Generally just going to the board and taking down a stop sign will stop the unwanted behavior before anything has to be said to the specific student. The blank for the rule # can be filled in with a dry erase marker (if laminated), or just copy enough that the student can hang on to the warning.