Wow you made that site? Very nice and professional looking! All I did was take the quiz (I think I know it pretty well) and it was great! It seems that the next button doesn't like me very much when I was going over the answers.

A couple improvement ideas:

A skip to question button. 55 questions is a lot, and anyone else that pushes "last" button halfway through won't have to push back repeatedly. (When that happened to me, I started taking the quiz backwards, it wasn't worth the time to go back).

Also, in the "arrange these in order" it would be nice for it to slide things in at the beginning instead of switching each time. If you forget C, you pretty much have to redo the question.

And just an idea: maybe something with piano keys (although not everyone is familiar with pianos, hmmm...) or staves?

Overall, very nice! I'd reccomend it my students, if I had any! I'll work on that...

Thank you verry much I understand it now.
I love learning new things and this is
something that i will use.
Thank you

<Added>

having it in bass clef, tenor clef and alto clef would be great.