Meet Jackie Robinson and solve a mystery in the #1 bestselling Magic Tree House chapter book series!   PLAY BALL! Jack and Annie aren’t great baseball players . . . yet! Then Morgan the librarian gives them magical baseball caps that will make them experts. They just need to wear the caps to a special ballgame in Brooklyn， New York. The magic tree house whisks them back to 1947!   When they arrive， Jack and Annie find out that they will be batboys in the game—not ballplayers. What exactly does Morgan want them to learn? And what’s so special about this game? They only have nine innings to find out!   Discover history， mystery， humor， and baseball in this one-of-a-kind adventure in Mary Pope Osborne’s New York Times bestselling Magic Tree House series lauded by parents and teachers as books that encourage reading.   Magic Tree House books， with fiction and nonfiction titles， are perfect for parents and teachers using the Core Curriculum. With a blend of magic， adventure， history， science， danger， and cuteness， the topics range from kid pleasers (pirates， the Titanic， pandas) to curriculum perfect (rain forest， American Revolution， Abraham Lincoln) to sea...