Miss Slovak is retiring from teaching, because she wants to become a professional golfer, and Mr. Simmons becomes the new fourth grade teacher. Mr. Simmons is very sensitive and has a "be your own unique self" teaching method, which bores the students. He also encourages the students to always ask "Why?" Eventually the students rebel against Mr. Simmons, and eventually break him and he quits. However, when the class leaves, Arnold stops and starts to feel bad for Mr. Simmons as he stares at the school window sad and heartbroken. However, their next teacher, Mr. Goose, or Lieutenant Major Goose, is a strict disciplinarian who teaches with a strict military "One unit" method. The students now realize how good they had it with Mr. Simmons, and they try to apologize to him, but Mr. Simmons is not convinced. However, after they prove that they've learned what he's tried to teach them, he reconsiders. The students then gang up on Goose, bombarding him with the "Why?" questions that Mr. Simmons encouraged, and eventually he is overwhelmed and quits. But the students are delighted when Mr. Simmons returns to teach fourth grade again.