Charlie doesn't return for the new school year and the Kids are wondering where's Charlie? Charlie found an acting gig and left and now the students have a new teacher, Billy MacGregor.

When Alan is caught cheating, Billy has the class act as a jury to decide his punishment.

Arvid goes out with gorgeous Viki.

Arvid's infectious flu may keep the class from performing in a Shakespeare competition.

Billy tries the personals ads.

Inspired by his French class, Eric goes to ""find himself"" in Paris.

Billy fakes a heart attack to circumvent a health-insurance bureaucrasy; the IHP girls try writing a romance novel.

After Billy is robbe, he has the class write papers on gun control, leading Arvid to a harrowing experience when he buys a gun for the assignment. (Part 1 of 2)

Bully Zach may have Arvid's missing gun. (Part 2 of 2)

The IHP class behaves obnoxiously when their bus breaks down at a rural truck stop.

Jasper's overprotective parents hire a babysitter for him -- and to his mortification, it turns out to be Sarah.

Billy and Bernadette take dance lessons at the studio where Alex teaches, and where he's pursued by a woman.

Arvid trains a chimp at his part-time pet store job and, rather than let it be sold, hides it in the classroom.

Simone's reputation suffers when Alex lies to his friends about a romance with her.

At Christmas, Billy helps Viki find her birth mother, but the woman doesn't want to see her.

T.J. turns down Aristotle's invitation to the senior prom.

The kids work on their yearbook, with Eric beginning to regret not having participated more extracurricularly.

To save Dennis after a prank, Billy creates a fictional student -- who apparently gets the MIT scholarship Dennis wanted.

The class learns T.J. is more than just a contemporary-style musician when Billy discovers her operatic talent.

With a wrecking ball ready to demolish the school, the IHP class waits to fund out who's to be valedictorian. (Part 1 of 2)

The IHP class graduates, with T.J. as valedictorian. (Part 2 of 2, and series finale)