This is a chart that I use in my elementary level library. I attached all of the colored papers together and then use a brightly colored clothespin to visually show where the noise level of the class is.
The way I use this is as a reward system and I gave each color a point value. If the class stays on green the whole time they earn five points. Each time I need to move the clip to yellow the class loses a point. If I ever need to move the clip to red the class loses all of their points.