Using the example of an undergraduate unit of study that is taught both on-campus and externally, but uses Internet-based learning in both cases, we explore how social media might be used effectively in higher education. We place into question the assumption that such technologies necessarily engage students in constructivist learning; we argue that the affordances of social media must be complemented by "social" affordances, designed into the learning experience, which thereby generate the necessary connection between students' motivations to study and their motivations to exploit social media. We demonstrate, via the example given, how assessment structures and strategies are the most effective focus when attempting to create the pedagogical affordances that might lead to collaborative learning. (Contains 3 notes.)