This Demonstration displays the equivalency of degree and radian measures for angles. The radius of the circle can be modified to emphasize that the radian measure of the angle is the actual length of the subtended arc when the radius of the circle is 1. When the radius of the circle is not 1, the radian measure of the angle is not equal to the arc length of the subtended arc but rather gives the arc length divided by the circles radius. Tick marks appear along the circumference to emphasize the units being used to measure the angle.