<![CDATA[The limited problem-solving skills of elementary school students in Natural and Social Sciences (IPAS) learning remain a major challenge in implementing 21st-century education. This study aims to: (1) examine the effect of applying the Problem-Based Learning (PBL) model assisted by Pop-Up Book media on students' IPAS problem-solving skills, and (2) compare the improvement in problem-solving skills between a class taught using the PBL model assisted by Pop-Up Book and a class taught using the Discovery Learning model assisted by PowerPoint. The study employed a quasi-experimental method with a nonequivalent control group design. The sample consisted of 60 fourth-grade students from SDI Imam Ahmad bin Hambal, Subang Regency, divided into 30 students in the experimental class and 30 students in the control class through purposive sampling. The research instrument consisted of 12 essay items developed based on Polya's problem-solving indicators. Data analysis included normality tests, homogeneity tests, independent sample t-tests, N-gain tests, and simple linear regression analysis. The results showed that the experimental class achieved a posttest mean of 82.22 compared to 70.00 in the control class, with a t-test significance value of < 0.001 (p < 0.05). The N-gain value for the experimental class was 0.4967 (moderate category), higher than the control class's 0.1989 (low category). The regression test showed a significance value of 0.000 with an R Square of 0.419, indicating that the PBL model assisted by Pop-Up Book contributed 41.9% to the improvement in students' problem-solving skills. It is concluded that the application of the PBL model assisted by Pop-Up Book media has a positive and significant effect on the IPAS problem-solving skills of elementary school students.]]>
