You could do this through the students if you wanted as well..... We have so many different levels of talent here.... You could post a song and ask what key it is in and someone could tell you. From there you could go to work. Report back periodically for feedback and direction..... Just a suggestion. I have tried it in the past, and found it to be very helpful. I don't have the greatest ear for music, but once I know a key, it sure makes transcribing a lot easier.
MJ