Here is a site that I found on Music theory. Here is the link for music theory.net . Music theory for young musicians (as well as seasoned verterans) can be the bane of their existence. Music theory is the complex building blocks for all of the music that we know and love.
There are lots of site that have basic theroy skills such as note recognition and key identification, however, this site offers everything from the very simple fundamentals to the most complex of advanced theory that would be offered in advanced music theory classes.
As I explore this site more, I hope to find that it will be a useful resource for my students. There are many elements to this site and I see that it is very complete in terms of theory. We shall see what it holds and I dig deeper into it.