Hi Betty, I always think you have 3 basic choices for organization: by discipline--drawing, painting, ceramics etc. or by Art Elements and Principles, or by the Thematic approach.
Since they have never had art classes it might be a good idea to structure your assignments around teaching the E&P's. You might look at what they will do in the next few years in art classes and base your decision on that. I mean, if they have to do E&P's for the next 3 years, do something else.