When you are helping a student, often times multiple hands will raise. This leaves students sitting at their desks watching and waiting for you to finish. To solve this problem, I put the "I'm Next" sign on a cabinet. I have numbered cards, so that each student who needs help can take a number. They place the number on their desk. This allows them to keep working. When I am finished working with a student, I begin calling numbers. The student with the corresponding number comes up for help and places his/her number back on the hook.