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

As students build an understanding of the proportional relationship between radians and degrees, they have an opportunity to attend to precision of language in their descriptions (MP6).

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