good info, but lacking design
here's a small critique:
the animation is very informative and the topic is great, but what you are lacking is better design in both your user interface and your text/illustrations. this can keep your animation looking more classy and less like a powerpoint presentation.
the placement a lot of the text is inconsistant from frame to frame, plus it is the same boring user console font type seen every. you may able to use most stylish fonts as headings to juice up your typigraphical design.
another thing the quality of your imported pictures. some of them are pixelated (bass clef) or have the "standard, boring" white background. get rid of those, nothing screams pulled off the internet more than poor resolution and a badly cropped jpeg.
a finally, the greatest thing about flash is that it is fun, that means user-interactivity. maybe adding buttons that play pitches, "click to learn more" submenus, or a section where you can make your own sheet music. just "continue" and "back" buttons are maybe a little too bland.
the animation for revealing the first menu is awesome, and i'd like to see more of that with every slide.
all and all a good presentation and i can't wait to see what you make next