I liked Discovering Art History - by Gerald Brommer - from Davis Publications.
There is another good one by Janson (I think many of us used Janson in college).
I know one of the area high schools here uses History of Art for Young
People - Janson and Janson. Sax has that one listed. Slide sets are
Sax also had History of Art by Janson.
Since you are ordering class sets, contact the company (on school
letter head) and ask for examination copies. I know Davis will send
one. I don't know who you would have to contact for examination copies
of Janson's books.
Looks like the good old Getty list is back now .... I will go into "lurk mode"
Anyone who really needs me knows where to find me. Thanks to everyone
who kept it going during the rough time.