Head of the Class

The opening of the show features various New York landmarks as well as Charlie Moore's journey to work every day. Charlie lives in a building in Hell's Kitchen occupied by a plant distributor on the first floor, who gives him a ride to the subway at 50th Street on the back of the truck before he makes his first delivery of the day. After Charlie grabs a hot dog for breakfast, he begins running into trouble as the subway station is on fire and he cannot hail any taxis to take him to the school. Forced to walk out of frustration, Charlie arrives late to class to the chagrin of Dr. Samuels but once he enters the classroom, his expression immediately brightens as he sees the students. In season two, the names of the characters portrayed by their respective actors/actresses were added to the credits. After three seasons with the same opening, it was changed to a group photo of the class for season four. After Hesseman left the show, it was changed to notebook graphics for its final season. The school used in the exterior shots is Washington Irving High School in Manhattan.

• Howard Hesseman – Charles P. "Charlie" Moore (seasons 1–4). A history and social studies teacher who teaches the honors program to intellectual geniuses and helps them aim for their dreams.
• William G. Schilling – Harold Samuels. The high school principal similar to a pushy parent who wants his IHP students to win Academic Bowl. He is Mr. Moore's boss, as well as a friend.
• Jeannetta Arnette – Bernadette Meara. The vice principal of the school who is friends with Charlie.
• Leslie Bega – Maria Borges (seasons 1–3)
• Dan Frischman – Arvid Engen
• Robin Givens – Darlene Merriman
• Khrystyne Haje – Simone Foster
• Joher Coleman (credited as Jory Husain) – Jawaharlal Choudhury (seasons 1–3)
• Tony O'Dell – Alan Pinkard
• Brian Robbins – Eric Mardian
• Kimberly Russell – Sarah Nevins
• Dan Schneider – Dennis Blunden
• Tannis Vallely – Janice Lazarotto (seasons 1–3; guest, season 5)
• Rain Pryor – Theola June "T.J." Jones (seasons 3–5)
• Michael DeLorenzo – Alex Torres (seasons 4–5)
• Lara Piper – Viki Amory (seasons 4–5)
• Ke Huy Quan (credited as Jonathan Ke Quan) – Jasper Kwong (seasons 4–5)
• De'voreaux White – Aristotle McKenzie (seasons 4–5)
• Billy Connolly – Billy MacGregor (season 5). Billy takes over Mr. Moore's class in season 5. He is from Scotland and, just like Mr. Moore, helps the students aim for their dreams.

• Marcia Christie – Lori Applebaum. A pretty, bubbly student not in the IHP whom Arvid has a massive crush on ... and everyone, including Lori, knows it. Seen in seasons 1 and 2, then reappears in the finale.
• Peter Vogt – Mr. Dorfman. A Fillmore High teacher who is somewhat self-centered and not especially respected. Appears occasionally in seasons 1-3, and reappears in the series finale.

Most of the students' parents were seen during the series, but usually in one episode apiece. Parents who appeared more than once included:

• Enid Kent – Maureen Foster (Simone's mother) (three episodes)
• J. Patrick McNamara – Mr. Foster (Simone's father) (two episodes)
• Bruce Gray – Dr. Enric Engen (Arvid's father) (two episodes)

Out-of-work actor Charlie Moore began the first season as a substitute teacher, but warmed to the IHP class immediately, making it his mission to get them to think rather than merely to know. Although they are gifted academically, the IHP students had plenty of problems in their personal lives, and Mr. Moore not only is there to listen, he shows an ability to get the students to solve their own problems while making it seem like they came up with the answers on their own. By Episode 6 ("Teacher's Teacher"), the class's original teacher Mr. Thomas (Roscoe Lee Browne) had returned to Fillmore High, seemingly ready to return to the IHP class once Mr. Moore's tenure ended. After observing Mr. Moore's unorthodox teaching methods for most of the episode (much to Charlie's chagrin, as it also made apparent how much he would miss the IHP students), Mr. Thomas ultimately reveals he had no intention to return but came to observe Mr. Moore after hearing concerns about him from Dr. Samuels. Seeing Mr. Moore in action, Mr. Thomas gives him his blessing, leaving Mr. Moore to become their full-time teacher, knowing the IHP will be in good hands. Throughout the first season, Mr. Moore attempted to get the class involved in more than just their studies, encouraging them to play volleyball and make a music video for the school's time capsule (this marks the first foray into the fondness of Head of the Class for musical production numbers). At the same time, the class brought Mr. Moore into the present, acclimating him to the importance of personal computers. Near the end of the season, the IHP faces their Russian counterparts in an academic tournament, foreshadowing their famous trip to Moscow in season three.

Season 2 began involving the IHP in the school as a whole, with Mr. Moore involving the class in the school literary journal and encouraging a lampoon of the school newspaper. Mr. Moore also decides to put on a school production of the musical Grease, and encourages the IHP (who are initially reluctant) to participate, alongside other Fillmore students.

While first season had some episodes that showed Charlie's personal life outside school, these become increasingly rare as the series continues. In season 2 (and thereafter), episodes consistently focus on the lives of the IHP students, with only a very few focusing specifically on Charlie; this is the last season in which we see Charlie's apartment.

In 1988, Head of the Class broke new ground as it became the first American sitcom to be filmed in the Soviet Union with an episode filmed entirely in Moscow.[2]

The IHP is invited to come to the country for a rematch of the academic meet that happened in season one, which ended in a tie. The class has a lot of experiences while in Moscow: Dennis and Arvid take an interest in two beautiful women, until they realise they might be KGB spies; Eric meets up with his relatives in what is a very positive experience for him; capitalist Alan has an argument with a die-hard socialist in a store (who is also on the opposing Russian academic team); Sarah and Darlene decide to record the sights and sounds of Moscow; Simone goes to put flowers on a poet's grave and meets up with a charming Russian musician; Dr. Samuels believes that his hotel room is bugged, but ends up making a fool of himself; and Charlie has a brief romance with a schoolteacher.

The IHP eventually wins the meet and the respect of the Russian team. The episode concludes with both teams attending a concert in Gorky Park swaying to the song "Far Away Lands" (written and performed by American David Pomeranz and Russian rock star Sasha Malinin).

The fourth season saw some significant changes to the cast of characters. Maria went to a performing arts school, Jawaharlal moved to California, and Janice went to Harvard as a sophomore. Several new characters took their place: Alex Torres (Michael DeLorenzo) was a Hispanic athletics student, portrayed as having an eye for the ladies. Although Alex seemed attracted to Darlene particularly, both he and Eric competed for the affection of another new IHP student, the blonde hippie Viki Amory (Lara Piper). Another new character was aspiring filmmaker Aristotle McKenzie (De'voreaux White). T.J. Jones (Rain Pryor), a recurring character since the third season, joined the IHP in the fourth season (a remedial student with a streetwise attitude, T.J. was found to be smart enough to join the IHP). Also, the character of Jasper Kwong (Ke Huy Quan) was added to the IHP class late in the season. The season also showed them film a two-part episode at the NASA Johnson Space Center in Houston, Texas. The students' final year of high school was split over seasons four and five. Howard Hesseman left the show after the fourth season. As Hesseman noted in a 1989 interview, "We're not doing the show that I was led to believe I'd do, and it's difficult for me to get off that."[4]

In the first episode of season 5, Scottish teacher Billy MacGregor (Billy Connolly) arrived to replace the departed Charlie Moore (in the first episode of the season, it is explained to the dismayed IHP students that Mr. Moore's acting career finally took off). Despite initial uncertainty and some hostility from the students, Billy proved to be a successful replacement for Charlie. He usually comes into the class bringing his bike. He insisted that the students refer to him by his first name, and although he was more rousing and less laid-back than his predecessor, he proved to be just as wise and caring (Billy also had a habit of boisterously greeting his class every morning with the phrase, "good morning, geniuses", and facetiously barking to his students to, "get out of here", when the bell rang at the end of the class. He also taught his class in a manner more akin to a stand-up comedian than a teacher). Many episodes from this season focused on Billy having to adapt to living in America and his attempts to romance Ms. Meara. Other aspects of Billy were his dislike of an outdated French textbook, which actually prompted one student to take a spur-of-the-moment jaunt to Paris, and his encouragement to the male students that the best way to get girls was to be themselves. The season (and the program itself) concluded with the IHP students graduating from high school. Janice Lazarotto (from seasons one–three) returned for a guest appearance in the finale, in which T.J. is named class valedictorian and the school is closed down and demolished.

In November 2020, it was reported that Isabella Gomez was cast in the lead role as teacher Alicia Adams. Coincidentally, Gomez and Howard Hesseman (who played Charlie Moore in the original series' first four seasons), had both starred on the television series One Day at a Time, with Hesseman starring in the original series' final two seasons as Barbara Cooper's father-in-law Sam Royer, while Gomez starred in the 2017 reboot as Elena Alvarez.[9] It was also announced that Watchmen actress Jolie Hoang-Rappaport will join the cast as student Makayla Washington.[10] In December 2020, it was announced that Little Fires Everywhere actor Gavin Lewis will join the cast as student Luke Burrows.[11] In January 2021, Jorge Diaz, Dior Goodjohn, Brandon Severs, Adrian Matthew Escalona and Christa Miller joined the cast.[12] The October first look revealed that Givens would be reprising her role as Darlene from the original series.[13]