This is one of the simpler of a huge number of elegant GeoGebra creations from Daniel Mentrard. (Those available in HTML rather than Java are here.) You're given an angle which is some integer multiple of pi/12 and asked to place it on the appropriate place on a circle. You then push the test button to see if you've placed it correctly. You can choose between "Stage 1" and "Stage 2" problems. Stage 1 has only positive angles. Stage 2 includes negative angles.