The Greedy Triangle (Scholastic Bookshelf)
I've probably read this one a hundred times!
Kids will get their early math skills in shape with this bestselling picture book--now available in Scholastic Bookshelf! Bored and dissatisfied with his life, a triangle visits a local shapeshifter to add another angle to his shape. Poof! He becomes a quadrilateral. But then he gets greedy and keeps...