I like the variety of courses. My son will be taking the bio and chem labs. There are advantages and disadvantages to the Keystone program. I like the ease of teacher contact. I don't like the expense.
Courses are mainly appropriate in content but a couple have been toooooo easy.
A study guide accompanies the textbook and provides a breakdown for the work. Self testing materials are in the study guide. If I had it to do all over again, I may have chosen AS but the variety of the classes makes for a very well rounded student. We used Keystone for a few single courses this year and were moderately satisfied. From what I've researched it sounds as if American School would be as good or better and cheaper as well.