Moosic"" is the answer to the question in the title, perfectly reflecting the goofy tone of this worthy sequel to the father-and-son team's first book of riddles, Riddle City, USA! (1994). Beginning readers will have their curiosity piqued by the inventive questions (""What are soft, white visitors from Mars?"") and more than satisfied by the answers (""Martian-mallows""). Funny illustrations accompany each riddle, with loafing bread, grinning bugs, and smiling ships. The Maestros have captured the silliness and wordplay children of this age enjoy; the bonus is that they can read them to each other. A great addition to the venerable I Can Read series.