I see the dilemma for you then. Not all educational success stories are about individuals becoming good students, but I digress. Perhaps studying this by trying to create a course or set of courses that somehow isolate the computer classroom angle isn't the way to go. It would seem to me that the only way that a study could really get at this question would be if it were longterm and covered a wide range of classrooms. Collecting data from a variety of similar institutions, comparing changes in retention rates with external factors, collaborating with others who might want to do similar studies in their own classrooms.
Audiences expand the mythologies of a creator's world.