Mrs. Howell is not familiar with how operant conditioning is really a description of events and the impact on rates of behavior. If she had been better informed about operant conditioning, she might have realized she was operating a punishment contingency or procedure. When she provided students with warnings or went ahead with withdrawal of an item already in hand, she was making consequences contingent on disruptive behavior.
Numerous behavioral studies have shown that punishment is a suppressive mechanism only. It is not a procedure for increasing positive or desired behaviors that generalize across settings—in this case, classes in an elementary school.