Epistemic artefacts of a physical nature are the material evidence of the work done and produced by students in the course of their learning. According to socio-cultural theory, they can mediate student participation and learning. The role they play, and what this tells us about new forms of teaching such as active learning (AL) in new environments such as active learning classrooms (ALC), had not been explored previously. We used a case study research design and ethnographic methods with 19 instructors from three colleges to explore three research questions based on this gap in the literature. Qualitative coding technique as well as latent class analysis were used to analyse the data, i.e., classroom observations (N=157). Our results confirmed that AL teaching generates physical artefacts. Furthermore, these artefacts play an epistemic role in learning and teaching. Our analyses distinguished four features of these artefacts, expressed as bi-polar modalities: (1) individual and/or collective; (2) private and/or public; (3) analogue and/or digital; and (4) new and/or reused. Other analyses led to more results. It is important to note that the public modality appears to be the most critical for understanding the mediating role of artefacts. We discuss the implications of these public artefacts on how learning and teaching takes place in ALCs and provide suggestions for practitioners using AA pedagogies in ALCs.