A worrisome Casey is having difficulty writing her valedictorian speech for graduation. Meanwhile, Edwin is concerned that he won't be able to live up to Derek's reputation at J.S. Thompson High when he goes there in the fall.
As the prom approaches, Casey and Derek both find themselves without a date. Meanwhile, George and Nora have something to tell the family.
Derek serves as a chaperone for Casey who is going to a party in Toronto with Truman. Meanwhile, Lizzie goes out on a date with a boy that the family has never met.
To be eligible for college athletic scholarships, a "D" average Derek seeks George and Edwin's help in passing all of his final exams. Meanwhile, Nora and the girls try to get a stressed out Casey to stop over-studying and relax.
A surprise visit from Edwin's friend Teddy turns into a frequent occurrence that makes the entire McDonald-Venturi household uncomfortable. Despite warnings from Emily, Casey decides to go out on a date with Truman.
After entering a tv dance contest, Casey must find a new dance partner when the previous one pairs up with her rival. Meanwhile, Lizzie dares George and Edwin to eat only healthy food for a week.
While his parents are away for the weekend, Ralph stays at Derek's home where he begins to develop a crush on Casey.
As George prepares a Mexican fiesta for their second wedding anniversary, Nora gets a reluctant Casey to tell the story of how she and Derek first met.
Casey gets stuck with Truman as her fencing partner in gym. Meanwhile, what starts out as a friendly game of table-tennis between Derek and Edwin turns into an ongoing competition to figure out who is the best player.
Casey spends the day with George at his law office where her need to organize things doesn't mesh well with the way he usually does things. Meanwhile, Derek tries to help Nora land a business deal with a client.
Derek plans to drop of out of school to be with Sally in Vancouver.
Derek breaks up with Sally after she reveals her plans to attend a university in another province. Believing that he is hurt over what happened and is bottling up his feelings, a concerned Edwin and Casey try to get him to open up. Meanwhile, Lizzie and Marti attempt to keep a dog hidden from most of the family.
Life with Derek is a Canadian television sitcom that aired on Family and VRAK.TV in Canada and on Disney Channel in the United States. The series premiered on Family on September 18, 2005, and ran for four seasons, ending its run on March 25, 2009. The series starred Michael Seater and Ashley Leggat as the two oldest children in a stepfamily. It ended with 70 episodes and one spin-off television film, entitled Vacation with Derek.