Hi Malcolm,
Sorry but I don't really understand what you want to do and I'm not even sure the Questionnaire module is the best suited for your purposes.
It would make it easier (for me) to understand if you could provide some mock-up concrete examples.
For instance, let's say in your Moodle course (the concept of "class" of students does not exist in Moodle parlance) you have divided the students into group A (6 students), group B (6 students) etc. Now, what question are you going to ask of your students in Questionnaire? What question type will you use? What will be the text of the question(s)?
Joseph