A clever introduction to geometry encourages readers to use some common household objects as props to define different kinds of triangles, quadrilaterals, and other polygons. All of the concepts are demonstrated using a toothpick, a slice of American cheese, pretzel sticks, a round sheet of paper, a piece of graph paper, and a pencil. Tobin's bightly colored illustrations and Adler's occasional bad puns ("Now that's what I call a square meal!") add touches of humor without overwhelming the sound information. (Ages 8-10)