This paper explores the introduction of peer-led group learning to final year undergraduate Biology students undertaking extended projects. Students were encouraged to use a virtual collaborative environment – Slack – as a hub to share ideas / findings and to ask questions. The research used survey and activity logs, combined with focus groups and interviews. We compare the learning outcomes from two cohorts, focusing on the frequency and nature of interactions within Slack among group members and with the facilitator. We discuss the implications of our observations for instructional support to students and the transferability of this model to other disciplines.