Episode Title:The Magic School Bus Flexes Its Muscles.Episode Description:The bus is acting up, so Ms. Frizzle decides to take it to R. U. Humerus' Body Shop for repairs. Meanwhile, Ralphie has been dreaming what it would be like if he had a robot to do all his chores. So he and the rest of the class (minus Keesha) want to try building one using all the gadgets in the body shop. First, they'll have to understand how bones and muscles work, though.