Gr. 5-8. With a clean, attractive format, the World of Mammals series features concise chapters accompanied by color photographs (many of them excellent) from a variety of sources. In a departure from most books of wildlife, the first chapter of polar Bears discusses the bond between the animal and the Inuit people, who have depended on hunting the bears for survival. Then the discussion turns to the bears themselves: their physical features, behaviors, and relatives as well as the threats to their survival. A world map indicates the polar bear's habitat, and a glossary, classification chart, and short lists of recommended videos and books are appended. Though written in brief sentences, the text will be difficult for some middle-grade students.