Teaching with Moodle

Apologies for cross posting to other forums but I'm not sure which is the best for my query.

As part of my PhD I am evaluating how my students use Moodle to collaborate on assignments. I would like some help in this evaluation of students perceptions and their views on using Moodle. I am thinking of setting up some focus groups but has anybody done anything similar. What types of questions did you ask your students?

Thanks

Joe