To celebrate its 20th anniversary, Scholastic is re-releasing the ten original Magic School Bus titles in paperback. With updated scientific information, the bestselling science series ever is back!

Arnold has swallowed the Magic School Bus! Now, instead of seeing an exhibit of the human body at a museum, the class is taking a look at Arnold's stomach, his intestines, his bloodstream, and more from the inside on this heart-stopping fieldtrip - one the reluctant Arnold would be happy to miss.