This participatory design-based research study addresses the relational character of the physical learning environment and pedagogical practice in the context of a design project carried out at a Swedish upper secondary school. Three teachers initiated the project with the intent to introduce student centred pedagogy and increase active learning. In collaboration with the research team, they designed and furnished a classroom supportive for communication and intense interaction between students, and where students and teachers could work and construct knowledge together. Drawing on observations, video recordings and design conversations with the teachers, the analysis, which is inspired by Actor Network Theory, concentrates on the six month period when the teachers started to teach in the new classroom with focus on their experiences, asking what they experienced as advantageous and challenging. Considering the new learning environment as a network of socio-material relations consisting of a) physical and spatial agents, b) organisational structural agents, and c) teacher/teaching agents, we conclude that whereas some actors corresponded well and contributed to a well-coordinated classroom practice facilitating the project's intentions, some actors contradicted each other and challenged the same intentions.