Abstract
This study employed design-based research, comprising two design cycles to empower teachers' agency when they are engaged in STEAM lesson design. Cycle-1 focused on the application of a principle of “sustained idea-developing discourse” (SIDD) in an online knowledge building environment to foster teachers' “professional agency within teacher communities” (PATC). In cycle-2, generative artificial intelligence (GAI) was additionally integrated into the SIDD processes within the teacher community. The findings in cycle-1 indicated a general lack of interdisciplinary knowledge among the teachers for effective STEAM lesson design. The online collaborative discourse mainly focused on shallow idea-sharing and the PATC was not significantly enhanced. Nevertheless, with GAI integrated in the SIDD process in cycle-2, participants exhibited more elaborated, synthesis-oriented discourse actions, with significant enhancements in PATC. Overall, these findings emphasize the significance of GAI support in fostering SIDD for empowering professional teacher agency during their STEAM lesson design. The findings offer educators a more profound understanding of how to constructively use GAI for professional development in teacher communities.