This brightly illustrated book from frequent collaborators Adler and Miller quickly presents several math concepts related to fractions, decimals, and percents. Using a county fair as a backdrop, Adler discusses how to change a number in one form to its equivalent in another; and how the value of a digit depends upon its placement in relation to a decimal point. Miller's digital artwork illustrates the ideas clearly, though the profusion of color and pattern is occasionally distracting. Offering a more active approach to learning equivalents, the final page shows how to make a simple memory game and directs readers to the illustrator's Web site, where colorful cards are available for downloading. Because the book includes several different lessons, it will be most useful for review of concepts already learned.

Adler and Miller easefully tackle yet another aspect of mathematics with clear explanations and graphic interpretations that extend the topic of an earlier book of theirs, Working with Fractions (2007). Here the author draws the connection between fractions, decimals and percents using money as a convenient vehicle to express parts of a whole. The illustrator sets the action at a county fair with electric colors and sharp, two-dimensional edges. The price of goods at the fair serves to launch the discussion of how 89 cents becomes 89/100 becomes .89 becomes 89 percent. Gradually more complicated material is introduced—numerator, denominator, position relative to decimal point—and then how one finds decimals and percents when the denominator isn't 100. Times when a particular use predominates is explained, and a few pop quizzes are administered to give readers a sense of grasp and accomplishment. The team's sense of sheer fun gives the book significant propulsion, the county fair conveys an assuaging atmosphere for those with a touch of math anxiety and the quizzes offer an enjoyable challenge. Both straightforward and bouncy, a successful primer on parts. (Picture book. 6-10)