How Radians Work

I can take NO credit for this, but it was powerful and I would love to have it on reference if/when I ever teach Alg II, Trig, or Pre-Calc.

I tried to find the original source and found it on Wikimedia's open source files page:
http://commons.wikimedia.org/wiki/File:Circle_radians.gif

It makes me feel better to know I'm not stealing someone's work without documenting it!

I am not writing lessons for this, as I think this is best left as an amazing resource for students and teachers when they need a visual way to explain and envision radians.

Grade Level: 10-12

Course: Algebra II, Trig, Pre-Calc

Standards: F-TF.1, F-TF.2, G-C.5,
SMP:  SMP2, SMP4

Skills: Radians, Making sense of the unit circle