<![CDATA[Purpose - This study aims to critically examine the commonly reported effectiveness of replacing expository teaching with problem-based learning (PBL) in Islamic Religious and Character Education classrooms in Indonesia. While previous classroom action research studies frequently associate PBL implementation with improved student participation, this study investigates whether increased engagement is consistently followed by improved learning achievement. Design/Methodology/Approach - The study employed classroom action research based on Lewin’s cycle, comparing a baseline lesson using lecture-based instruction with a subsequent learning cycle implementing problem-based learning. The research was conducted in a class of fifteen grade-eleven students at a private senior secondary school in Purwakarta, West Java. Data were collected through structured observations of teacher and student activities, student questionnaires, achievement tests, and documentation. Quantitative data were analysed using descriptive statistics, while qualitative data were examined through thematic analysis. Findings - The findings indicate that the implementation of problem-based learning improved classroom participation and teacher adherence to the instructional model. Student participation increased from 50.00% to 66.66% of the observation scale, while teacher implementation increased from 43.33% to 56.66%. However, the improvement in learning achievement was limited, with the mean score increasing only from 26.66 to 30.66. Furthermore, classical mastery decreased from 46.67% to 40.00%, as the number of students achieving the minimum threshold declined from seven to six students. These results suggest that increased classroom engagement does not necessarily correspond with improved knowledge acquisition. Originality/Value - This study provides a critical perspective on Indonesian classroom action research literature, where increased participation is often interpreted as evidence of instructional success without sufficiently examining its relationship with academic achievement. By revealing a divergence between engagement and learning outcomes, the study contributes to a more balanced understanding of problem-based learning implementation and supports the need for evaluating both process and achievement indicators in instructional innovation research.]]>
