Previously the authors have reported on the merits of involving student teachers in school-based curriculum development projects (McCullagh and Doherty, 2018; Earle and McCullagh 2020; McCullagh and Doherty 2021). These projects have involved up to 20 primary science specialist student teachers planning and teaching lessons in a small number of local primary schools. The students and teachers worked together to develop and evaluate teaching strategies and resources, which could continue to support in-service teachers long after the project was completed. Evaluations of this work have consistently shown a great increase in the student teachers' competence and confidence as well as substantial benefits to the host teacher and the science provision of the school. Their latest project, the 'Student Teachers Supporting Primary Science Project', involves 228 student teachers in the first (106) or second (122) year of their four-year undergraduate degree programme in primary education, and teachers from 209 primary schools from across Northern Ireland. Financed by the Royal Society of Chemistry's Outreach Fund, the project aims to explore whether the same impact could be achieved when an entire cohort of undergraduate students works with a much larger group of schools.