Track the facts about the unicorn of the sea–the narwhal–and its closest relatives!When Jack and Annie came back from their adventure in Magic Tree House #33: Narwhal on a Sunny Night, they had lots of questions. What is a narwhal? Why is it nicknamed the unicorn of the sea? What other whales live in the arctic? How do they survive the cold? Find out the answers to these questions and more as Jack and Annie track the facts about narwhals and other whales.Filled with up-to-date information, photographs, illustrations, and fun tidbits from Jack and Annie, Fact Trackers are the perfect way for kids to find out more about the topics they discover in their favorite Magic Tree House adventures.Did you know that there’s a Magic Tree House book for every kid?Magic Tree House: Adventures with Jack and Annie, perfect for readers who are just beginning chapter booksMerlin Missions: More challenging adventures for the experienced readerFact Trackers: Nonfiction companions to your favorite Magic Tree House adventures