<![CDATA[ABSTRACT Critical thinking skills need to be developed through IPAS learning that provides students with opportunities to engage with problems, process information, and formulate solutions. A learning environment still dominated by lecture-based methods was found among third-grade students at SD Negeri 02 Pelemkerep, Jepara Regency, resulting in learning activities that have not yet optimally trained these skills. This study aims to analyze the implementation of the Problem Based Learning (PBL) model on the critical thinking skills of third-grade students in the IPAS subject. The study employed a quantitative approach with a One Group Pretest-Posttest design and involved 14 students selected through a saturated sampling technique. Data were collected using a critical thinking essay test, observations, and interviews, and were subsequently analyzed using the Shapiro-Wilk normality test and the Paired Sample T-Test with the assistance of SPSS version 25. The results showed that the mean critical thinking score increased from 50.71 on the pretest to 81.79 on the posttest. The Paired Sample T-Test yielded a significance value of 0.000 (<0.05) with a calculated t-value of 9.352, indicating a significant difference in students' critical thinking skills following the implementation of PBL. These findings indicate that PBL can serve as an alternative approach to IPAS learning that supports student engagement in problem solving and the development of critical thinking skills. ABSTRAK Kemampuan berpikir kritis perlu dikembangkan melalui pembelajaran IPAS yang memberi kesempatan kepada siswa untuk menghadapi persoalan, mengolah informasi, dan merumuskan penyelesaian. Kondisi pembelajaran yang masih didominasi metode ceramah ditemukan pada siswa kelas III SD Negeri 02 Pelemkerep, Kabupaten Jepara, sehingga aktivitas belajar belum optimal dalam melatih kemampuan tersebut. Penelitian ini bertujuan menganalisis penerapan model Problem Based Learning (PBL) terhadap kemampuan berpikir kritis siswa kelas III pada mata pelajaran IPAS. Penelitian menggunakan pendekatan kuantitatif dengan desain One Group Pretest-Posttest dan melibatkan 14 siswa melalui teknik sampel jenuh. Data dikumpulkan menggunakan tes esai berpikir kritis, observasi, dan wawancara, kemudian dianalisis melalui uji normalitas Shapiro-Wilk dan Paired Sample T-Test dengan bantuan SPSS versi 25. Hasil penelitian menunjukkan rata-rata kemampuan berpikir kritis meningkat dari 50,71 pada pretest menjadi 81,79 pada posttest. Uji Paired Sample T-Test menghasilkan nilai signifikansi 0,000 (<0,05) dengan t hitung 9,352, sehingga terdapat perbedaan kemampuan berpikir kritis yang signifikan setelah penerapan PBL. Temuan ini menunjukkan bahwa PBL dapat menjadi alternatif pembelajaran IPAS yang mendukung keterlibatan siswa dalam pemecahan masalah dan pengembangan kemampuan berpikir kritis.]]>
