No need for radians to be mysterious. Scholars use a cardboard cut-out of a unit circle and measure the radius and circumference using a piece of string. They consider the number of radii needed to cover the entire circumference and use the results to develop a concrete definition of radians.

Concepts

unit circle, radians, central angles, arc length

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Additional Tags

math

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Instructional Ideas

• Have classmates complete the first activity (creating the cardboard unit circle) as homework if time is an issue
  

Classroom Considerations

• Pupils should be familiar with unit circles
• Materials such as cardboard, string, scissors, screwdriver, protractor, and straightedge are necessary
  

Pros

• Provides a data sheet for learners to fill in
• Includes a rubric for the activity
  

Cons

• None

Common Core

HSG-C.B.5