Pi

Gr 5–8—These books cover the history of each number's use in mathematics, from early approximations and similar concepts in the ancient world up to and including contemporary thought. Brief chapters with large pictures on every spread contrast with sophisticated vocabulary, much of it not defined in the glossary. Cunningham names, but does not explain, several mathematical ideas such as calculus and transcendental numbers. While a few of the illustrations illuminate concepts or enrich the text, many seem barely relevant: a photograph of the Parthenon, for instance, in a section discussing ancient Greeks' astronomical calculations, or an image of a unicycle used to illustrate the scientific advances of the 19th century. Captions occasionally give insufficient or even incorrect information, as when an image of a pentagon is labeled "six sides" in Pi. Without these errors Pi could support schools and libraries that host Pi Day (March) celebrations. Back matter includes brief biographies of the eight mathematicians discussed per book.—Sarah Stone, San Francisco Public Library