This is a variation of a mystery walker poster. I have it laminated and hanging right by the door, along with a set of popsicle sticks with each student's name. Whenever we line up to leave the classroom I pull a stick, but keep the name to myself. I watch that student while they are in line. When we return to the classroom if that student followed directions and acted appropriately in line then the class earns a link. Our class links are attached to a bulletin board and when the links touch the floor then the class earns a reward; extra recess time, popcorn party, etc. We usually vote ahead of time on what the reward will be and then I remind them that they have to work together to earn it.