Sustainability is a complex, ill-defined concept that has been the subject of much debate over the last two decades (Wals and Jickling, 2002). The ill-defined nature of sustainability manifests itself within socio-scientific issues where conflicting reality constructions, values, norms, and interests interact. Initial teacher education as part of Higher education has a responsibility to critique the values and knowledge claims inherent within contemporary science issues and can meet this responsibility by supporting students to engage with socio-scientific discussions within the context of learning for sustainability. This paper explores how forty-four primary education students engage with discussions focused upon climate change. Students' prior educational experience, together with their disposition towards open-mindedness impacts heavily upon the way they interact during discussions. Online teacher-mediated discussion fora are useful for supporting primary education students' ability to cope with the inherent complexity and the differing values imbued within the multiple perspectives emergent within socio-scientific discussion.