The class has gone to a drive-in movie to see the black and white B-film Stand by Your Mantis from 1953 featuring General Araneus (Ed Asner) who is attempting to destroy a giant praying mantis. Carlos and Phoebe are not enjoying it. he hates insects and spiders, and she is upset and declares that if she were in the movie, she would trap the praying mantis, take it somewhere else, and free it. Naturally, this gives Ms. Frizzle an idea. So she drives the bus into the movie. General Araneus takes over it, kidnaps Liz, and pushes a button that makes the class go back out of the movie and shrink. He wants to use Liz as bait for the praying mantis. Outside the movie, the class encounters a lot of spiders, and when Liz pushes a button that pulls them back into the movie, they apply what they have learned about spiders to stop General Araneus from using her as praying mantis bait.
