If I were teaching art history in high school I would try to find copies of
an old textbook called Understanding and Creating Art. It is a two volume set
intended I think for middle school. I used it with a year long eighth grade
class (it was a bit of a challenge for them) and have always wanted to use it
with an older group. The authors are Ernest Goldstein, Theodore H. Katz, Jo D.
Kowalchuk and Robert Saunders. It was published by Garrard Publishing Company
of Dallas Texas. It is, of course, years out of date, but I love the way the
books organize and present material.