Can you do the six civilizations briefly, then allow them to do a paper on whatever sounds most interesting to them/the one they'd most want to learn about? Or would that not work within the time framework? That was what I liked about the intro archeology class I took, that we covered a lot of shit and then got to research whatever most interested us for our final paper.

Random aside, what I thought was an eBook copy of the Eagle of the Ninth was actually just a five star review of the book; it was weird, but slightly amusing.