S03E23 - The Blackboard Bungle
Synopsis
Charles seems to be the only one excited about his new post as teacher's aide. Jamie resents his sitting in on her class, and the teacher, Marvin Merken (Jerry Van Dyke) , a burnt out man living on the hope that retirement comes before insanity, can't understand why anyone would want to teach. When a nervous Charles must cover for Merken, Jamie can't resist heckling him and he assigns her detention. The next day he tries to repair the damage and encourages discussion among the students. Merken enters, during the debate, horrified to find Charles encouraging the students to talk. Jamie, having cooled off overnight, sticks up for Charles' methods and the rest of the class agrees, resulting in Charles getting a good recommendation and Merken softening his attitude.