This is something I've tried to work into our "school" for a while and haven't been able to do for some reason.
But, now, well we are doing alright in that department. Basically my plan is this: We study one artist for 4 or 5 weeks looking at one piece a week. We are using a book called Discovering Great Artists to do one or two projects for each artist. Every morning during circle time (more on that later) we look at the piece of the week and each of us tells one thing we notice about it.
For the composer studies, we are using a fabulous website called Classics for Kids. We study each composer for 4 or 5 weeks. We listen to one show from the site a week and have one piece a week that we listen to.
It's quick, it's painless, it's easy.
And did you know that Bach had 20 children? Most of them were musicians also. That blows my mind for some reason.