I should introduce it, on second thought:
I wrote what was essentially a musician's guide to beginning music
theory on spec for an online freelance publisher, but they turned it
down. (They were looking more for "What's a staff" rather than "What's
a circle of fifths?")
Here it is, for what it is, on Google Docs.
http://docs.google.com/View?id=dgkwwmf7_79hjpvmkhj