Definition of bell ringers:
(n) :
(education) An assignment, done regularly at the beginning of a class, and intended as a warm-up before other classroom activities.
(n) :
A person, especially one of a group, who rings bells.
(n) :
(anatomy, education) A type of anatomy exam in which students must answer questions at a series of stations and move on to the next station when a bell is rung.
(n) :
(derogatory) A door-to-door salesman.