Teaching and assessing large classes can be reframed from focusing on overcoming difficulties with large classes, to seeking the unique educational opportunities provided by such learning environments. We discuss data and examples illustrating how active learning and formative assessment can be successfully embedded into the teaching of large groups. Students evaluated these approaches favourably, and recognised that their own learning was enhanced through being active participants in lectures and having opportunities to receive feedback on their understanding within lectures. Furthermore, the experiences of teaching staff using these techniques were found to be largely positive, demonstrating awareness of the benefits for students as well as benefits for their own engagement and development. These data suggest that if we find the unique opportunities for learning afforded by large groups, the lecture has the potential to become a powerful learning environment.