Pre-service and beginning in-service science teachers enrolled in a university teacher education program participated in a project to support their teaching through a lens of sustainability. While they demonstrated active and positive engagement, I considered the possibility of any students reacting negatively to the course material and doing so in ways that were silent and not easily visible. In preparing to avoid and, as necessary, respond to any evidence of such negative reactions in the future, I reviewed literature and contemplated how to create safe, empowering learning environments that welcome diverse and dissident perspectives, while upholding respect and intellectual engagement.