This project aims to investigate the development of primary teachers’ adaptive expertise in interdisciplinary mathematics and science. As a critical component of quality teaching, adaptive expertise is essential for teachers to innovate their teaching to enhance student learning and interest, yet little is known about its development. The project aims to explore how adaptive expertise can be fostered through classroom innovations purposefully codesigned by teachers and researchers in the context of interdisciplinary mathematics and science. Expected outcomes include a better theoretical understanding of adaptive expertise in the context of interdisciplinary mathematics and science to benefit teacher learning and improve student outcomes.