<![CDATA[This study aimed to analyze the effect of the Problem Based Learning (PBL) model integrated with Science, Technology, Engineering, and Mathematics (STEM) on students’ critical thinking skills in sound wave topics. The study employed a quasi-experimental method using a pretest–posttest control group design. The population consisted of all eleventh-grade students of SMA Negeri 1 Kuala Langkat in the 2025/2026 academic year. The sample was selected through simple random sampling, resulting in one experimental class and one control class. The experimental class was taught using the STEM-integrated PBL model, while the control class received conventional instruction. The research instrument was a validated critical thinking skills test consisting of 15 essay questions. Data were analyzed using normality and homogeneity tests, Independent Sample t-Test, Cohen’s d effect size, and N-Gain analysis. The results revealed a significant effect of the STEM-integrated PBL model on students’ critical thinking skills, as indicated by the posttest significance value of 0.000 (p < 0.05). The effect size value of 2.18 indicated a large effect. Furthermore, the N-Gain score of the experimental class was 0.7501 (75.01%), categorized as high, while the control class obtained an N-Gain score of 0.3701 (37.01%), categorized as moderate. Therefore, the STEM-integrated PBL model was proven to be more effective than conventional learning in improving students’ critical thinking skills on sound wave material.]]>
