The broad umbrella of active learning has been shown to support student learning and retention within in-person undergraduate classrooms. Rapid adoption of online course delivery has integrated some of the insights from previous research, but also raises new questions about the difference in active learning strategies between modes of course delivery. Here we present results of a systematic review of 87 published active learning studies from 2015 to 2025 that focus on in-person and online courses. We summarize the evidence for efficacy of interventions, class sizes, and methods of active learning. These data highlight gaps in knowledge and show opportunities to bring these insights into our own classrooms to meet the needs of students today and into the future.