This study examines the impact of school-based STEM learning modules on academic performance in Northern Ghana. A randomized controlled trial was conducted, with schools randomly assigned to either a treatment group (receiving the STEM modules) or a control group (no intervention). The analysis revealed that students in the treatment group showed an average improvement of 12% in mathematics scores and 9% in science scores compared to their counterparts in the control group. These findings suggest that school-based STEM learning modules can significantly enhance academic performance, particularly in mathematics and science subjects. Schools should consider implementing these modules as a strategy to improve student engagement and achievement in STEM fields. STEM education, randomized controlled trial, Northern Ghana, academic performance The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.