Math teachers have a new tool for teaching estimation in this manual designed to train the eyes and mind. In the “Eye Training” section, Goldstone uses photos of objects and animals to help readers recognize groups of tens, hundreds and thousands, and then presents several opportunities to practice this type of estimation. In “Clump Counting,” children see how much space ten (for example) of an object takes up, then how many groups of tens there are, to arrive at a good estimate. “Box and Count” is a similar method wherein readers are taught to visually divide a space into one hundred small boxes, count the objects within one and multiply by one hundred. Throughout, a hint box at the bottom of the page gives clues as to where to start, methods for proceeding and possible estimates. Perfectionists beware: Only one exact number is given in the entire book. A list of things to estimate gives readers a chance to practice their new skills in the real world. A must-have resource for school libraries. (Nonfiction. 7-12)
