Out-of-field physics teachers: A challenge and an untapped resource

Many secondary physics teachers in the US and globally are out-of-field (OOF) - trained in other disciplines like chemistry or biology but assigned to teach physics anyway. This situation harms both teacher well-being and student learning, making it a critical issue for education researchers and practitioners. Rather than viewing OOF teachers solely as a problem to be fixed, our research explores how their former disciplinary expertise can actually enrich physics education. We designed professional development activities that engage OOF teachers in dialogic argumentation with in-field physics teachers. The activities were specifically designed to allow different perspectives on physics problems and to encourage deliberation among the teachers. Analysis of these dialogues revealed surprising findings: heterogeneous groups of in-field and OOF teachers engaged in more deliberative dialogues than homogeneous groups of physics specialists alone. The OOF teachers brought valuable epistemic practices often missing from traditional physics instruction - particularly mechanistic reasoning and sophisticated experimental design considerations. These findings hold implications for supporting OOF teachers' professional development, and for advancing interdisciplinary teaching teams.