simple
the basics of reading sheetpaper, though still too simple i think
but well, its difficult to explain everything in 1 flash. if you plan to make any sequels, you may indeed go with more details or with different subjects etc.
if so, i would give you a 10 ;)
oh yeh, the graphics are nice
the B# etc does exist under certain circumstances, it depends on which music scale youre playing (one with lots of # for instance) or when the componist uses a certain modulation. (sorry, cant give you the exact music scale, i dont have a piano at my room, its at home)
i agree with the review below, some interactive things would improve very much: people tend to remember things better when theyve really done something, not by reading.
anyway, a nice try!
hope you make more, making more people to understand music (kind of)