I made these to post on my whiteboard in my classroom. I put them back to back, laminated them, and put magnets on both sides. When I am instructing, it is on the red side. The kids will know, hey I will have to wait until she flips it to the green side. This is a problem I had with my 3rd graders last year. This way they only know to ask when its red sign if it is an emergency and they can't hold it for the next couple of minutes. When it is on green side, they know they can check themselves out and quietly go without asking my permission. I have a sign in/out sheet and 2 bottles of hand sanitizer with "Girl's Pass" on one and "Boy's pass" on the other. They put the sanitizer at their desk, sign out, take the hall pass, and go. When they come back in, put the passes back, sign in, and resume work, all without interrupting class or me. And as a teacher you can see who is in the bathroom by where the bathroom pass is. Additionally only one boy and one girl is allowed in the bathrooms during class time because there is only one pass per gender. I also charge for using the bathroom pass with economy system to ensure they are going when they really need to go. If they have no money and it looks like an emergency, then I let them go. Be careful with this system. It seems flawless, but I have yet to try it out.