At Arnold's, Jenny comes in and walks over to a table where Joanie, Chachi, and Roger are sitting. She tells Roger that his car is about to be towed. He leaves to check it out. Al comes out of the kitchen, senses that someone left without paying his check, and goes outside. Jenny comes out of the restroom and tells Joanie that Noreen, the daughter of a minister, is pregnant. Noreen comes in and sits down at a table. Chachi thinks that this is just gossip. Joanie, Chachi, and Jenny leave as Fonzie comes in flanked by two women in military uniforms. Fonzie guides Chachi back in. Fonzie says he found the women at an army recruiting station. Chachi leaves. Roger comes back in and talks to Fonzie. His car was towed, and he needs to go get it. He asks Fonzie to cover for him teaching his hygiene class and says the lesson plans are on his desk. Roger leaves.
At Jefferson High, Tommy tells the class that they're getting a substitute teacher. He asks what they're going to do to the sub. Bobby has a can of snakes, but nobody goes for it. Tommy suggests they get rid of the lesson plan so that they don't have to take a test that was planned. A nerdy student stands up and protests saying that he studied many hours for the test and is prepared to take it. Chachi asks who he is, and he says he's Melvin Belvin, Eugene Belvin's brother. He says he hasn't been around for a year because he was home with an earache. Chachi tells him to sit down. Bobby has another idea: tell the substitute that Roger was teaching them sex education. They all are in favor. The bell rings, and Fonzie comes in. He says they're all too quite and asks what they've got planned. Melvin sucks up to Fonzie, and he guesses that he's a Belvin. Fonzie can't find a lesson plan, and Bobby tells them they were supposed to discuss sex education. Bobby says they left off at puberty.
Later in the discussion, Fonzie tells the class that they cannot let their bodies get in the way of their brains. Nobody understands. He illustrates his point on the chalkboard and tells them all to just stay in their houses. He says to think a little and not make any dumb mistakes. He asks if there are any questions. Noreen starts to ask a question, but the bell rings. Fonzie tells the class to wait until they're dismissed, but Noreen says the question wasn't important. Fonzie dismisses the class.
At the Cunningham house, Fonzie comes in with a couple of intercoms Howard and Marion can use to communicate with Fonzie. Fonzie compliments them on their appearances and the table setting. There are candles and wine, and it's set for two. Fonzie gets the picture and starts to leave when Roger comes in. He's upset with Fonzie saying that, because of him, he's going to be fired as a teacher.
Howard asks Roger why they're firing him, and he says that Fonzie taught sex. Melvin Belvin told his parents who told the principal who accused Roger of bringing in a guest smut-lecturer. Fonzie says he was only teaching what Roger already taught. Roger asks Fonzie if he even read the lesson plan, and Fonzie says there was no plan. He says they were enjoying the discussion, anyway. Roger says they were pulling Fonzie's leg. Fonzie says the joke's on him and says it's no big deal. Fonzie and Roger start eating Howard and Marion's romantic dinner. Marion says that Joanie is in that class, and Howard is visibly upset that Fonzie taught sex to their little girl. Fonzie says it was just a little mistake, but Roger says that he's now on probation. His classes will all be monitored as if he was a student-teacher. Fonzie says that all he did was answer a question, and Roger says that there are some answers you can't give unless you have permission from the school board. Howard says there are some things that just shouldn't be taught in the classroom, but Roger disagrees. He was just stating what the rules were. He had offered to teach a sex education class at the beginning of the school year, but he was turned down. Howard thinks sex should be taught at home, but Marion says it would have been nice to have a little professional help when she had the talk with Joanie. Roger says that some parents don't say anything to their kids, so the school should be able to take up the slack. Howard still doesn't agree and asks why they're not eating. Howard and Marion go into the kitchen. Fonzie tells Roger that he got the ball rolling regarding teaching students about sex and tells him to pick it up from there. Roger says he can't because he'll be fired if he does. Roger doesn't know what he'll do if he's asked a question like Fonzie was asked. Howard and Marion come back in with the main course of their dinner, and Fonzie and Roger sit down to eat it.
At Jefferson, three people from the board of education come into Roger's class to observe. Fonzie is also there for moral support. Roger tells the class they'll be discussing hygiene of the mouth. He begins talking about certain parts of the mouth and asks if anyone would like to point them out. Noreen raises her hand but has a question regarding yesterday's class. She wants to know how a person would know if she was in trouble. Roger says he would like to answer her question but says that that day's topic is hygiene of the mouth. He puts his pointer down and asks how many people have the same question as Noreen. Several girls and Melvin raise their hands. Roger says that it is a good question that deserves an answer.
Roger finishes up the discussion and says it will be the last time they'll talk about it in his class. He doesn't go into the moral issues of anything saying that that is best discussed at home with their parents. The bell rings, and Roger dismisses the class. Fonzie tells Roger that he did a great job. Noreen thanks Roger for clearing everything up because she thought she could become pregnant by necking with a boy while wearing a bathing suit. She says her mother told her that. She thanks him again and leaves. A woman named Mrs. Eckhardt comes in and tells Roger that he won't be fired. She had overheard Noreen talking to Roger and hadn't realized the naiveness of some of the kids and that they were too embarrassed to talk to their parents. She says she'll recommend that there be a voluntary class of that sort. Mrs. Eckhardt says they could use more teachers like Roger in the school system. She tells Fonzie that he is unique.
Songs in this episode:
"You Are My Sunshine" by Ray Charles (1962)
"My Boyfriend's Back" (instrumental) by The Angels (1963)