"Mr. Kotter, Teacher" finds Mr. Woodman unhappy with Gabe's relaxed teaching methods, putting him up against the school board for review. Acting as arbiter on the case is Miss Riley (Hope Summers), while speaking for the defense is science teacher Charlie Piper (Arnold Soboloff). When things begin to look bleak for the accused, each of the Sweathogs parade through the door, Horshack in blonde Harpo Marx wig as the window washer, Epstein and Washington posing as the painting Linguini brothers, Barbarino as the female janitor, singing "O Solo Mio" as he barges in! (the 'What-Where' routine while he's wearing a skirt and bosom). Kotter and Epstein do Groucho and Chico as Woodman suffers his latest nervous breakdown. Kotter explains how normal methods don't work with these kids, who are not stupid but underprivileged: "a dumb person does not think of a way to make it rain in the gymnasium!" (Barbarino: "I did that!"). After further review, Miss Riley rules against Woodman and in favor of retaining Kotter.
