In this "First Facts, Why in the world?" nonfiction book designed for readers in kindergarten through third grade, each chapter is a question that is answered in several paragraphs along with accompanying photographs. The table of contents lists seven questions. A page at the beginning explains the process of scientific inquiry in simple steps. Questions such as "Why do some animals sleep all winter?" and "Where do animals hibernate?" are answered in simple sentences. The large photographs, such as the bear eating berries from a tree and a squirrel digging in the snow for buried nuts, will interest and entertain young readers. A "Can you believe it?" page explains how wood frogs live in spite of their bodies becoming frozen, and a "What do you think?" page asks the reader to think about ways people could use hibernation. Several "Did you know?" facts are given throughout the text. A short glossary is included, followed by a list of related books, Internet sites, and an index. Words printed in bold type in the text are listed with meanings in the glossary. Children will enjoy reading while learning in this introduction to essential scientific information about hibernation.