This provides a nice template on which students can practice graphing sine and cosine from the unit circle. The radian measures are delineated on the unit circle at intervals of pi/2 and the graph is as well. Students who have difficulty setting up neat graphs will find this particularly helpful but I use this with all my students so their time is spent understanding the concept primarily and not stressing over getting lines straight, etc. Once complete, this becomes a useful reference for students as they proceed in their study of trigonometry. These concepts come up not only in trig but also complex numbers and vectors. I am using this this year to teach my engineering students.