Happy Days - Season 9 - Eps 7: Fonzie, the Substitute
Fonzie substitutes for Roger in his hygiene class, and, as a prank, the students hide the lesson plan and tell Fonzie they're learning about sex. Roger is later informed that he will be fired as a teacher as a result of Fonzie's teachings.
About Happy Days

Title: Happy Days
First Air Date: 1974-01-15
Last Air Date: 1984-09-24
Status: Ended
Rating: 7.7/10 (from 274 votes)
Language: EN
Seasons: 12
Total Episodes: 252
Network: ABC
Genres: Comedy
Production Companies: Miller-Milkis Productions
Synopsis
In 1950s Milwaukee the Cunningham family must contend with Fonzie, a motorcycle riding Casanova.
Cast

Henry Winkler
Arthur Fonzarelli

Tom Bosley
Howard Cunningham

Marion Ross
Marion Cunningham

Anson Williams
Potsie Weber

Scott Baio
Chachi Arcola

Ted McGinley
Roger Phillips

Erin Moran
Joanie Cunningham