Topic: The Solar System. Arnold's cousin Janet joins the class on a trip to explore the solar system.

Topic: Digestion. Arnold's so excited he doesn't have to go on a field trip! But when he accidentally swallows his miniaturized class, he becomes the field trip.

Topic: Germs. Ralphie is crushed when a fever keeps him home from school the day he's scheduled to host a FNN (Frizzle News Network) television broadcast on health. With Tyne Daly as Ralphie's mom.

Topic: The Food Chain. Arnold and Keesha are in trouble when they forget to bring in their assignment on "two things that go together."

Topic: Habitats. When Wanda's pet frog, Bella, jumps out an open window, Ms. Frizzle shrinks the bus into a mechanical frog and takes her now tiny class on a hop-along adventure.

Topic: Decomposition. It's "Accidental Science Project" day and the class has brought in marvelously rotten entries from the backs of their refrigerators. With Ed Begley, Jr. as Larry Log-Away.

Topic: Desert Adaptation. Always the caring soul, Phoebe goes on a crusade to save the animals and plants of the desert -- and discovers how well they take care of themselves.

Topic: Sound. The class is thrilled about its upcoming concert at the Sound Museum -- until they discover the spooky mansion is more of a thrill than they bargained for. With Carol Channing as Cornelia C. Contralto.

Topic: Kitchen Chemistry. It's Ms. Frizzle's birthday, and a field trip to the bakery seems perfect -- until the bus' shrinkerscope goes on the fritz and the class gets baked in a cake. With Dom DeLuise as the Baker.

Topic: Forces. Ms. Frizzle combines Dorothy Ann's physics and Ralphie's baseball into a "Frictionless Baseball Game".

Topic: Seeds. The class' garden is going to be featured on the cover of "Plant It" magazine. But Phoebe's garden plot is glaringly empty. With Robby Benson as Mr. Seedplot.

Topic: Ants. The Magic School Bus goes into show business when Keesha directs a movie about social animals for the school science fair.

Topic: Weather. The Friz transforms the bus into a Weathermobile and -- in a wild ride through the skies -- Ralphie becomes the meteorological superhero of his dreams.