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 like coordinated pencil dropping, switching names, and chanting in unison that his lessons are bogus. They break his spirit when Harold steals and eats his sandwich and the students run out like wild animals. 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.
The next day after Simmons quit, Principal Wartz then announces their new teacher will be Mr. Goose. The class is initially humored at the name, but the laughter stops when they see that Mr. Goose, aka Lieutenant Major Goose is a strict disciplinarian who teaches with a strict military "One unit" method. Anyone that acts out even slightly is sent to a corner (even if they didn’t do anything so that the corners are symmetrical) and the students have to say the times tables in unison.
The students now realize how good they had it with Mr. Simmons and that his ideas and methods weren’t as bad as they initially thought. They go to his house and try to apologize to him so that he can be their teacher again, but Mr. Simmons is not convinced. However, after they prove that they've learned what he's tried to teach them, he reconsiders and decides to come back to teaching. However, they still needed a plan to force Goose to quit. The students then gang up on Goose, bombarding him with the "Why?" questions that Mr. Simmons encouraged, and eventually he’s overwhelmed, decides to quit and runs out of the classroom screaming. But the students are delighted when Mr. Simmons returns to teach fourth grade again.
