Robertson 
Squares and Triangles [PDF ebook] 

In Square and Triangles, readers will learn how shapes show up in everyday life. This 24-page title features colorful visual aids, simple text, comprehension and extension activities, and more to effectively engage beginning readers and reinforce the basics of common shapes. The Concepts: Shapes and Numbers series takes the learning of basic concepts to the next level. By connecting colors, counting, and shapes to what children know will result in greater understanding. Colors looks at the colors found in different seasons, Counting introduces children to the different ways they can count their favorite things, and shapes allows them to be creative and see what they can build.