After Zack opens his medicine cabinet one morning and sees a boy who could be his double staring back at him, he enters a parallel universe.

After an electrifying experiment in science class gives Zack a shock, he realizes that he can read other people's minds.

When his friend Spencer, the class genius, spends the night, he and Zack discover how to leave their bodies and travel around New York City, but they have one problem--how to get back inside themselves.

When Zack goes to a store to buy a baseball card, he finds himself face-to-face with his future son who has traveled back in time.

When Zack uses a magic box from Tibet to produce a duplicate of himself, he finds that he has created more problems than he has solved.

When Zack accidentally drinks the invisible ink that is one of Spencer's experiments, he worries about missing his only chance to get his picture in the paper, if the new flavor he and Spencer invented wins the local Len and Larry's Ice Cream contest.

Late one night when ten-year-old Zack hears strains of "Heartbreak Hotel" coming from the refrigerator, he discovers the possibility that Elvis lives on as a turnip.

While on a class picnic in Central Park, ten-year-old Zack gets a chance to study ants close up and personal when he uses way too much of a classmate's diet powder and shrinks to their size.

After falling through his computer screen, Zack travels back in time to a school in 999 A.D. where the students believe the world will end in the new millennium.

When Zack is bitten by a tick during a class trip to Central Park he succumbs to Rhyme Disease, which causes him to speak only in rhymes and to float like a helium balloon.

Ten-year-old Zack has his body taken over by a British queen and quite a humorous adventure follows.

When magic enables Zack's eighty-eight-year-old grandmother to become a terrific batter, she ends up playing in a Chicago White Sox baseball game.

There's something weird about Zack's new friend Icky. It's not just the bandages or the Egyptian writing--but it might have something to do with being 3,000 years old!

A few days before his school's Halloween dance, Zack meets a girl who seems to be already wearing her costume.