When a Line Bends...a Shape Begins

In this well-conceived, bouncy and colorful primer, Greene (Barnyard Song) builds up various geometric figures from a line, the simplest element of every shape: ""A line is thin. A line is narrow--/ curved like a worm, straight as an arrow."" Each spread acquaints readers with a single shape, from a square to a triangle to a circle. Beyond the basics, there are ovals (""An oval's like a circle, except it's not as stout. Two sides go in to make it thin. Two other sides go out""), diamonds (""A ballerina's legs form one when bending at the knees"") and crescents (""It is a smile when curving up, when down it is a frown""). The introductions stop, appropriately, with a red octagon (""you see it at the corner. It tells the cars to wait""). Like concrete poetry, each verse takes on the shape it describes. Kaczman, in a remarkable picture book debut, incorporates images with sharp angles and smooth curves in full-bleed double-page spreads that orchestrate all of the elements of Greene's text. His precise renderings, evenly filled ink blocks and animal characters suggest J.otto Seibold's computer-generated geometric forms; however, his watercolors are slightly mottled, creating a grainy texture. In this clever and fun introduction to the assorted shapes, Greene and Kaczman collaborate effectively, clearly expounding an oval, square or octagon through bouncy rhyme, familiar examples and clean-edged artwork. Ages 4-8. (Sept.)