Student-led online courses present exciting learning and engagement opportunities compared to traditional teacher-led online courses. Teaching behaviours that emerge from learners are a major contributor to the success of such courses, complementing the work of facilitators. Our goal is to explore the teaching behaviours manifested by learners and facilitators and how these are affected by, and can be consequently supported through, a combination of automation and social structures. We examine data from three student-led courses supported by different online learning environments (a) mainstream loosely-coupled social media, (b) a custom-built learning platform and (c) a combination of both. We adapt existing cognitive and social taxonomies introducing a unified lens through which teaching behaviours can be identified and explored. We conclude with recommendations for course and learning environment designers to best utilise the affordances of selected learning environments in supporting pedagogy in student-led courses.