<![CDATA[Purpose: This study examined the effects of Kosifacay media-assisted Problem-Based Learning (PBL) on fifth-grade students’ learning interest and conceptual understanding of the properties of light. Methods: A quasi-experimental study using a Matching Only Pretest–Posttest Control Group Design was conducted with 43 fifth-grade students from two public elementary schools in Blora Regency, Indonesia. The participants consisted of 15 students in the experimental group and 28 students in the control group. The groups were naturally formed classroom groups located in different schools, and random assignment was not feasible. Data were collected using a 20-item learning interest questionnaire and a 30-item conceptual understanding test. Data were analyzed using descriptive statistics, paired-samples t-tests, and MANOVA with Pillai’s Trace. Findings: The experimental group showed increases in both learning interest and conceptual understanding following the intervention. MANOVA indicated a statistically significant multivariate difference between the instructional conditions in the combined outcomes (Pillai’s Trace = 0.733, F (2, 40) = 54.870, p < .001). Research Implications: The findings suggest that integrating Kosifacay media with PBL may support affective and cognitive outcomes in elementary science learning. However, the unequal group sizes, lack of random assignment, and implementation across different schools limit causal interpretation and generalizability. Originality: This study provides empirical evidence on the integration of Kosifacay media and PBL to address learning interest and conceptual understanding of the properties of light within an elementary science context.]]>
