Inside the Earth is the second book in the book series. It was written by Joanna Cole and illustrated by Bruce Degen. It was published in 1987.
The kids in Ms. Frizzle's class have been studying animal homes for almost a month. It's a relief when she announces, "Today we are going to start something new." They are going to study Earth science.
For homework, the kids are supposed to bring in rocks. But when they show up with everything from concrete to muddy Styrofoam, Ms. Frizzle decides it's time for a field trip. All aboard the bus! They dig through the Earth's crust, then travel straight to the core and out the other side--through the mouth of a volcano!
- This book was featured as a featured book in a 1990 episode of PBS' Reading Rainbow, and was narrated by Keisha Knight Pulliam (who also narrated Arthur's Eyes). It was considered the television introduction of The Magic School Bus (four years before the official television adaption).
- This book and And the Climate Challenge are the only two classic books to have their episode adaptations in Rides Again.
- In Reading Rainbow, the book has few minor changes, including how it was before the official publishing. Such as, even though in the book Phoebe is shown to be “the new kid”, the sign saying that as well as having an arrow pointing at her on the bottom of her feet has been blurred out. And pages that are never even in the book itself appear in the Reading Rainbow episode.
- Phoebe's regular outfit in this book would carry over to the 1994 series as her default outfit.
- Phoebe is a new student. This is her first appearance in the book series, and will later go on to become a student in the 1994-97 TV series' incarnation of Ms. Frizzle's class. However, her TV canon counterpart goes back to her old school in a later episode.
- On the other hand, that is likely the inspiration for her catchphrase "At my old school..." used in later books and the 1994 series.
- This book was adapted into the episode, "The Battle for Rock Mountain". It is about geology, but has an entirely different storyline.
- The drill bus does make an appearance in in the episode about photosynthesis.
- The book was also dapted as the computer game Explores Inside the Earth.
- This book was not present in the trailer for the ninth book (shown on NTSC-U VHS releases for season 2 of the prequel series), during the part when it listed the classic books.
- This book is featured in the MSB “Visit Your Local Library” book promo for Seasons 1-4 after the funding credits.
- In the reprinted version, the Bus's overhead sign says DIG IT!
- This is the first book to have a different cover image on republishings from 1997 to the present.
- On the reverse cover for the original 1987 hardcover publishing, Wanda and Phil are seen in the cave with a few bats flying around. On the 1992 paperback, the two bats, along with Wanda, were covered by the list of other books in the series and leaving out Phil.