Background: Formative assessment promotes positive learning outcomes and evaluates students over time. We aimed to evaluate students' learning achievements after implementing a formative assessment technique by using a normalised gain method. Methods: This retrospective observational study was conducted at the School of Medicine and Health Science, Faculty of Medicine, Prince of Songkla University, Thailand. There were 118 fifth-year medical students who attended a general pediatric course in the 2021-2022 academic year. Results: In the summative assessment, the post-test scores were significantly greater than the pretest scores (mean difference 20.53, 95% CI (18.63-22.44), P < 0.001). The median value of the overall student learning gain (g) was 0.34 (0.23, 0.45). Students with medium gains had significantly higher scores than those with low gains (P < 0.001). Students' learning gains had a positive correlation with post-test scores. (R = 0.6, P = 0.01). Conclusions: The formative assessment technique is a valuable method for enhancing students' learning outcomes by offering timely and effective feedback through mentoring systems. It is essential to integrate formative assessments into standard assessment strategies in undergraduate medical education.
