I like this system much more than the standard color change chart that I have used in the past because it is SO clear about your expectations for the students. This makes it ideal for the primary teachers classroom.
The posters describe the following...
C- conversation - what should the voice level be?
H- help - how do I get help?
A- activity - what are you working on?
M- movement - how can I move around the room?
P- participation - how do I participate in the lesson?
It is also very easy to use as a teacher. Buy some circle magnets to put on each poster. Move the magnet along the poster based on what you need the students to be doing for the lesson. I found some HERE that match PERFECTLY with the posters
You can purchase these CHAMPS posters HERE.