Rectangles are a useful shape, indeed. Stackable and sortable makes this shape easy to use. They're on the paper we write on. They're the shape of our walls. Easy text and large pictures help early readers discover that rectangles are fun! Translated by native Spanish speakers--and immersion school educators. Aligned to Common Core Standards and correlated to state standards. Abdo Kids Junior is an imprint of Abdo Kids, a division of ABDO.