This thesis investigates social learning in large scale courses, from the perspective of exploiting the benefits of massive participation. Specifically, I examine the affordances of the FutureLearn course platform, analysing their impact on learner interactions. I then create new affordances through a novel mediating artefact, the Comment Discovery Tool, and develop innovative pedagogical models which are refined through 3 phases of design-based research. The Comment Discovery Tool is an interactive visualisation of all learner commentary that allows learners to see conversations and emergent themes from the course in a non-linear fashion. In the second phase of design-based research I use formal learning design frameworks to introduce inquiry and reflection activities into the pedagogical toolkit. These are generally missing from the established model of large scale course design which values completion, progress and retention only. The third phase of design-based research continues the pedagogical innovation by encouraging learners to alter their writing style towards the development of communities of ‘ambient affiliation’. This demonstrates that learning at scale requires a reconceptualisation of online courses, placing massive-ness and cooperation at the heart of the pedagogic design. This thesis is a case study into how this can be achieved by using design-based research, placing learners at the centre of the design process, and levelling up the human activity of learning to one where learners can extend the range of their own environment for the benefit of others. The research represents an original contribution because I demonstrate how real-time visualisations can encourage cooperative activity and demonstrate how pedagogical innovation can be achieved through a rigorous user-centric analysis, starting from the materiality of the platform, and integrating theoretical frameworks. I also use a GPL open-source licence for the tool which enables others to download, remix and re-use the technology on other courses.