Topic: Dinosaurs. Ms. Frizzle takes the class on a dinosaur dig, courtesy of her old school chum, paleontologist Dr. Carmina Skeledon, and travels 67 million years back in time.
Topic: Bats. When Ms. Frizzle invites the class' parents in to see that their kids are learning about bats, Ralph and the gang are convinced the Friz is a vampire.
Topic: Butterflies. The class needs a new mascot for its soccer team. Phoebe suggests butterflies, but everyone thinks they're wimpy--until the Friz flutters in.
Topic: Energy. The class is ready to plug in their "Double-Trouble Wheel of Wonder" at the town carnival, when they discover all the electrical outlets are taken.
Topic: Space Rocks. When Dorothy Ann warns the kids there's an asteroid headed straight for their school, Ms. Frizzle arranges a friend trip into space.
Topic: Warm/Cold-Blooded. Liz has gone off to a mysterious place called Herp Haven. Thinking she's in trouble, the class rushes to Herp Haven, where they turn into reptiles.