With bright illustrations and clear, kid-friendly language, this book introduces one of the most basic geometric shapes to young readers. Formed of three sides and three angles, triangles are everywhere—especially on the pages of this book, where two kids and their robot friend assemble a brand-new bot from different types and sizes of triangles. This title defines important geometry vocabulary in simple, accessible terms, reinforcing the text with illustrations of the different types of and relationships between triangles. Activities on identifying, measuring, and comparing angles help readers understand these important ideas. Drawing on his years of experience teaching math, David Adler's text thoroughly introduces fundamental mathematical concepts. Colorfully illustrated by nonfiction veteran Ed Miller, this book is perfect for readers just beginning to study shapes and geometry.