STEM Project-Based Learning in Optics Education: Achievement and Student Perceptions in a Quasi-Experimental Pilot Study

STEM Project-Based Learning has emerged as a promising pedagogical approach for fostering students’ conceptual understanding and engagement through authentic interdisciplinary learning experiences. However, evidence regarding its implementation within curriculum-integrated secondary school physics remains limited. This exploratory quasi-experimental study investigated the preliminary outcomes of a STEM PjBL intervention for Grade 11 students during a geometrical optics unit through an authentic engineering project centered on liquid lens technology for small spacecraft. A quasi-experimental design was employed with two intact Grade 11 classes (n = 16 per group): one receiving STEM PjBL instruction and one receiving conventional instruction. Students in the experimental group demonstrated significantly higher post-test achievement than those in the control group (mean difference = 22.56 points, 95% CI [12.61, 32.52], p < 0.001), with a large effect size (Cohen’s d = 1.66, 95% CI [0.85, 2.46]). These findings provide initial evidence that a curriculum-aligned STEM PjBL intervention may be associated with higher achievement in secondary physics; exploratory perception data were descriptively more favorable in the experimental group, although some items reflected activities specific to that condition. Because each instructional condition was implemented in only one intact class, the contribution of the intervention cannot be separated from class-specific factors. The findings should therefore be interpreted as exploratory associations rather than as evidence establishing a causal effect of the STEM PjBL intervention. The study shows that, in one specialized secondary school, an authentic, technologically advanced engineering project was successfully implemented within the regular curriculum time allocated to the optics unit, warranting further investigation in other settings.