One of the initial promises of MOOCs was to enable participants from around the world to learn and build knowledge together, however existing MOOC platforms are very limited in their collaborative functionality. Using a recent educational modeling language which can express a broad diversity of educational scenarios, we present a technical infrastructure design and prototype which enables instructors to design and run pedagogically rich and therefore complex scenarios. We present this as a theoretical and technical contribution to support a broad program of research and innovation related to collaborative learning at scale.