How can you build on young children's interactions with the world to develop their geometric thinking? What can you say to a student who claims that a diamond isn't a square because it "stands on a point"? How can knowing what does not change when shapes are transformed help you extend your students' thinking about the area of geometric figures?

How much do you know... and how much do you need to know?

Helping your students develop a robust understanding of geometry and measurement requires that you understand this mathematics deeply. But what does that mean?

This book focuses on essential knowledge for teachers about geometry and measurement. It is organized around four big ideas, supported by multiple smaller, interconnected ideas—essential understandings.

Taking you beyond a simple introduction to geometry and measurement, the book will broaden and deepen your mathematical understanding of one of the most challenging topics for students—and teachers. It will help you engage your students, anticipate their perplexities, avoid pitfalls, and dispel misconceptions. You will also learn to develop appropriate tasks, techniques, and tools for assessing students' understanding of the topic.