Contains four episodes that follow Ms. Frizzle and her class on their science adventures aboard the magic school bus where they go inside the human body.

In these episodes from the hit animated series, the Cat in the Hat leads Nick and Sally on journeys of discovery in which they learn about the world's littlest creatures, such as earthworms helping the environment, spiders spinning their webs, limpits holding on tightly, fireflies lighting their world and microscopic protozoa in a dew drop.