Ups and Downs: A Book About Floating and Sinking

Is there a monster living in Walker Lake? That's what Ms. Fizzle's class is trying to find out. The kids try to dive down under the water, but the bus won't go! The class has to figure out how to turn their floater into a sinker so they can solve the mystery of the underwater monster. Take a dive with the Magic School Bus, and learn why things float and sink!