My own music theory articles got stuck when I got a job that took all my time, and I couldn't get them past a certain point. But I recently stumbled across a pretty good series of articles on learning to read music.
You may have heard the old joke:
How do get a guitar player to turn down?
Put sheet music in front of him.
That said, I know many guitar players who read sheet music jut fine, and they always have an advantage in learning new tunes over those who don't. The same goes for every instrument.
Here's the introduction to the articles on Kitchen Musician:
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Written music notation can be thought of as the ultimate tablature system. It works for any instrument, including the voice.
The music notation system we use originated in the Middle Ages, and caught on like wildfire.
Music used to be part of the core curriculum of a good classical education, along with mathematics, geometry and astronomy.
Some people think that the invention of music notation led to the invention of algebra.
It's practical. If you read music, you can learn tunes from all those gif files on the world wide web and from books. You can write down your own tune collection so you don't forget tunes. You can scribble out the first few bars of all the tunes you know in a little notepad, to prevent the "I know that tune but I can't think of how it starts" ailment.
It's not difficult. Remember the old kindergarten song about "ABCDEFG, HIJKLMNOP,"? You only have to remember the first seven letters. Being able to count with your shoes on is handy, but you rarely will need all your fingers.
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I agree 100% with the notions expressed above. So if, somehow, music reading was overlooked in your eductional background, click on the following link and get started.
http://www.kitchenmusician.net/tutor/tutor1.html