A Magic Mystery series is about a couple of kids who like magic tricks, Kate and Max. Kate is the one who considers herself a detective, and Max is the main magician with Kate as his assistant. Together, they use magic tricks and concepts in magic to solve their mysteries. In every book in the series, there is a section in the back with directions for performing the magic tricks in the story.
Most of the books in the series are also set on holidays: Thanksgiving, Mother’s Day, and Valentine’s Day.
The author of the series Elizabeth Levy, who also wrote many other books for kids, fiction and non-fiction, including the Gymnasts series and the Something Queer mystery series.
Books in the Series:

The Case of the Gobbling Squash (1988)
Max needs help from Kate when one of his rabbits goes missing around Thanksgiving.
The Case of the Mind-Reading Mommies (1989)
Max and Kate put on a magic show for Mother’s Day and solve a mystery involving disappearing presents.
The Case of the Tattletale Heart (1990)
The kids’ class is having a Valentine’s Day party, and Kate realizes that Max is keeping secrets from her.
The Case of the Dummy with Cold Eyes (1991)
Max and Kate add a ventriloquist dummy to their act and solve a mystery involving stolen jewels.