his paper analyses the inter-relatedness of layers of involvement, as contributing to learning, within a school sustainability project (the eco-classroom project). This engaged students, staff and community members (including professional practitioners) in an architectural co-design project that resulted, after 4 years, in a built classroom. The paper utilises an "ecology of learning" diagram to indicate layers and show connections, which are evidenced by findings from the project, alongside relevant literature in geographies of architecture and childhood, pedagogies of sustainable learning and children's participatory and co-design examples. In conclusion, the ecology of learning approach is critiqued and encouragement of more sustainability co-design projects with children is recommended. It is proposed this could lead to improved processes for all participants while promoting authentic and relevant sustainability learning.