Print the paddles onto thick paper, and cut them out. Fold the blank side over and make sure the paddles are not see-through from the back side. Give each student the 3 paddles (Yes, No, Maybe), during instructions, when you ask "Does everyone understand?" Have all your students hold up one of the paddles. If you see anyone holding up a yellow or red paddle, just start explaining anonymously to the whole class until they all understand. This is great for students who are too shy to admit when th