Lesson 12

Lesson Narrative

In this lesson, students strengthen their understanding of the relationship between radian and degree measures. They use double number lines and proportional reasoning to make connections between degrees and radians, then develop their intuitive sense of radian measures by shading sectors of circles with given radian measures.

Students have an opportunity to attend to precision (MP6) as they choose portions of a circle to shade in the Pie Coloring Contest activity.

It’s more important that students build their intuition around radian measurements than it is to develop a formal algorithm to convert between radians and degrees.

Learning Goals

Teacher Facing

• Coordinate (orally and in writing) between representations of angles measured in degrees and in radians.

Student Facing

• Let’s get a sense for the sizes of angles measured in radians.

Student Facing

• I understand the relative sizes of angles measured in radians.