Professor Flitwick teaches Charms and heads up Ravenclaw House. Like Professors McGonagall and Sprout, he chooses to quietly resist Professor Umbridge's reign of terror. When Harry prints his interview in The Quibbler, Professor Flitwick sneaks him "a box of squeaking sugar mice" (26.108).
Later, when Fred and George leave their giant swamp in one of the Hogwarts hallways before ditching school forever, Professor Flitwick refuses to remove it. Harry speculates: "teachers like McGonagall or Flitwick could have removed the swamp in an instant but, just as in the case of Fred and George's Wildfire Whiz-bangs, they seemed to prefer to watch Umbridge struggle" (30.2). In fact, once Professor Umbridge leaves the school, Professor Flitwick gets rid of the swamp in about a second – though he leaves a small portion roped off in monument to an excellent piece of magic.