We share our collective stories as instructors and graduate students with an interest in decolonial education on how we learned together in a course on Indigenous knowledge systems (IKS). The course occurred in the environmental studies department at a predominantly White graduate school in the Connecticut river basin in the area now known as the USA. The topic of IKS is steadily gaining interest in the environmental education (EE) field, as evidenced by an increase (albeit small) in the number of publications in peer-reviewed journals. At the same time, decolonial educators are looking for ways to teach IKS in an ethical and respectful manner. Our goal for this paper was to share how we grappled with questions around ethics and cultural appropriation. For instance, as decolonial educators who are not Indigenous to communities where we work and reside, can we facilitate lessons on IKS? If so, how can we do it in a manner that honors IKS and knowledge holders, is ethical, respectful and not appropriating? We learned that applying decolonization factors was crucial. Specifically, our work revealed four key decolonization factors: centering programs in Indigenous philosophies of education, privileging Indigenous voices and engaging Elders as experts, promoting Etuptmumk/two-eyed seeing, and employing Indigenous ways of teaching and learning. This paper makes contributions to the environmental education field, particularly decolonial educators who are seeking respectful and ethical ways to engage with Indigenous knowledge systems.