This exuberant picture book by Katherine Hannigan, the acclaimed and bestselling author of Ida B, is about math concepts, friendship, and imaginative play, and is told entirely in equations!A young girl and her dog spend the day playing in her backyard, where with her imagination--and a few helpful props--anything can happen. What do you get when you combine dirt and water? Mud! What do you get when you take a sheet, a flowerpot, and a stick and make a costume? You transform yourself into Her Majesty, the queen! A cape and a strong breeze turn the treehouse into an airplane. A sheet, a stick, and a pair of well-placed cat's ears turn the girl into a pirate! At least until mutiny leaves her alone in her kiddie pool . . . surrounded by sharks! Cheerful and action-packed illustrations and a combination of comic-like panels, conversation bubbles, sound effects, and full-page illustrations make Dirt + Water = Mud particularly appealing for new readers.