Unwrapping a Circle

This is a tool to help students envision the meaning of "radian" by thinking in terms of radius-lengths. To use: 1. Adjust length. 2. Adjust radius. 3. Guess the radian measure of the arc by envisioning how many radius-lengths the arc is in length. 4. Select "Show Radius Scale." 5. Move the "unwrap" slider to the right. By Ted Coe, tedcoe.com, 2011.