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 and sore throat keep him home from school the day he's scheduled to host an FNN (Frizzle News Network) television broadcast on health. Tyne Daly guest stars as Dr. Tennelli.

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.