T.J. is a boy genius who gets bumped up from the fourth grade to high school. T.J. tries to adjust to his new life, but he shares some classes with his 14 year-old brother Marcus, the school jock, and his clueless and self-absorbed 16 year-old sister Yvette.
T.J. is thrilled when he talks Brandi into joining the basketball team - until she replaces him as starting point guard, and he's relegated to the bench.
New romances are on the horizon for both Marcus and Mo in this episode. Marcus finds himself interested in Stacey, the new drummer for their band, while Mo's intended girlfriend rubs the other musicians the wrong way. Marcus is the one to suffer heartbreak first, leaving T.J. to try to pull him out of the doldrums.
Yvette and Mo hatch a plan to eliminate the competition in a radio station Volkswagen Beetle giveaway to the person who can stay inside it the longest. While they're in the vehicle, Marcus tries to take advantage of having the house to himself, but T.J. foils him.
When Floyd has to go out of town on business, Marcus tries to step in as the man of the house. T.J. poses some unexpected problems when he decides to court popularity by throwing a party for his classmates.
Mo gets the shock of his life when his parents tell him he's adopted, so he immediately enlists T.J. in his search for his birth parents.
T.J. is accepted into Mensa, where Floyd meets an attractive divorcÃ©e, but T.J. can't stand her uppity son Blake and gets into a brawl. Meanwhile, Marcus and Mo become hairstylists.
TJ becomes the new assistant to Coach Gerber when the math teacher finally quits. Meanwhile Yvette meets a guy named Calvin who she finds attractive who turns out to be in middle school.
T.J. is forced to take wood shop and finds out it's not as easy as he thought. Meanwhile, sparks fly between Yvette and a photographer.
When Floyd tells the kids to get a job, Yvette heads for a clothing store at the mall, while T.J. and Marcus set up a ""Homework Hotline,"" but they all encounter problems they hadn't imagined.
T.J. lands a gig as a dancer in a music video by Destiny's Child and gets an offer to tour with them for a year, but his dad isn't so sure about the idea.
Marcus and his girlfriend Dana break up, prompting her to ask Mo to intervene. Meanwhile, T.J. faces gym class - and the locker room - for the first time.
Computer snooping helps Marcus woo T.J.'s study partner.
Yvette has a recurring dream in which she marries Mo. Meanwhile, Marcus dreams up a scheme to make money to buy a new sound system.
A dejected Yvette decides she needs breast augmentation after another actress is picked for a plum stage role. Meanwhile, T.J. is harassed by bullies who make fun of his ears.
To enlighten Mo about feminism, Yvettle buys him at a school slave auction. Meanwhile, T.J. helps Coach Gerber do his taxes.
When Marcus sees Mo's girlfriend with another guy, he can't decide how to tell Mo. Meanwhile, T.J. thinks he's on the bad side of the Secret Service after writing an angry letter to the White House.
Marcus scores a date with the girls' volleyball team champ, but plays second string socially. Meanwhile, T.J. tries to boost Mo's brainpower.
T.J. develops his first crush on a beautiful substitute teacher; Marcus is accidentally offered a university scholarship.
T.J.'s call to a political talk show prompts an invitation to appear as a guest -- and to replace one of the regular panelists permanently.
Angered over rising machine soda prices rise, T.J. markets his own cheaper soft drink with the help of Yvette, Marcus and Mo.
T.J. plans a prank for graduation, while Yvette decides to boycott her graduation.
Floyd refuses to believe T.J. drank beer at a party with his pals.