Mr. Peepers shows up for his first day of work at Jefferson High and has initially a difficult time. His classroom isn't ready and the other science teacher wants him gone. Music teacher Miss Dean is welcoming and Principal Gurney wants to give him a chance.
Mr. Peepers agrees to give a speech on wildflowers for Mrs. Gurney at the same time Mr. Gurney needs him to play for a chess championship. Gym teacher Charlie develops a workout routine for Mr. Peepers but he gets stuck in a basketball hoop.
Mr Peeper's gets his hand stuck in a fish while trying to retrieve his tie pin. His bad day continues when his first paycheck get blown into an air pipe and he has to crawl in it to get it back.
The teaching staff pitches in on various custodial jobs when the janitor needs to be absent. Mr. Peepers is assigned to to run the striping machine which goes amok, leaving white stripes everywhere.
In Mr. Gurney's absence, Mr. Peepers takes a matter of student discipline to Vice-principal Velvet Clave. When he protests the harshness of the penalty, he finds himself out of a job.
On the strength of several published scientific articles by Peepers, a seed company agent tries to coax him to come work for their firm at a big salary increase over teaching. He declines when he finds he'd have to compromise his principles there.
Mr. Peepers asks Miss Remington to the school dance but the constant presence of Harvey Weskitt complicates things. And there is the matter of the broken punch dispenser.
Noticing a definite anti-social trend in one of his students, Peepers decides he's not getting enough fatherly attention, so he takes the boy fishing. A day of bungling only yields one undersized fish, for which the game warden brings them to court.