This study addresses a critical and underexplored area in STEM education literature by exploring the influence of a teacher-led, integrated STEM (iSTEM) programme within a formal school setting. Over a 14-week period, a cohort of 16 upper-primary classrooms in Ireland participated in an iSTEM programme incorporating educational robotics, the SUPERPOWERED programme. Utilising a pre- and post-test design, the study explored the influence of the programme on children’s STEM attitudes and career aspirations. The findings indicate no statistically significant change in either STEM attitudes or career aspirations. This outcome, however, is considered positive, as the children maintained pre-existing positive attitudes throughout the programme's duration. This research provides empirical evidence from a formal context, highlighting the challenges of measuring short-term attitudinal change. The results hold significant implications for future iSTEM curriculum design, emphasising the need for clarity in curriculum goals and a comprehensive understanding of the factors that shape children’s long-term engagement with STEM.