Lesson 6

Completing the Square

Lesson Narrative

Students complete the square to find the center and radius of circles. First, they look at a partially complete problem. They analyze what’s already been done and decide what steps must be taken to finish. Then, they execute the process on their own with no scaffolding.

As students interpret the partially complete work of completing the square, they are making sense of a problem (MP1). As they do the work of creating and rewriting perfect square trinomials to reveal properties of a circle, they are looking for and making use of structure (MP7).

Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.

Learning Goals

Teacher Facing

  • Calculate the center and radius of a circle by completing the square.

Student Facing

  • Let’s rewrite equations to find the center and radius of a circle.

Learning Targets

Student Facing

  • I can complete the square to find the center and radius of a circle.

CCSS Standards


Building Towards

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