If you've never taken a look at Squidoo, you may want to jump over to this page and take a look at the information I found on Music Lapbooks. There are loads of wonderful links to help you as you plan for group lessons, composer studies, or just want some information to help you share the study of the symphony orchestra. Much of the information generates wonderful ideas for your summer camps if you are starting to think in that direction!
There are entire unit studies on composers already put together for you such as this one done for Handel. All of the links, worksheets, etc. are all right there...just point, click and print! If you are looking for something in particular, just type it in the search. It will bring up more information than you can imagine!
Disclaimer: Beware! Once you get started, plan to be "surfing" for awhile as there are loads of wonderful links to follow with lots of great stuff!