I know some of us have a hard time knowing how to approach teaching art and music appreciation. I bought three or four curricula before I finally came to figure out a way that works for us.
Barb (a.k.a. Harmony Art Mom, also known from the Handbook of Nature Study online) has put together an intro to 6 composers and artists, Charlotte Mason-style, and is giving it away as a free PDF at her site! Go check it out.