<![CDATA[This study was motivated by the low learning outcomes in Natural and Social Sciences (IPAS) among fifth-grade students at SD Kristen 1 Waimahu, resulting from instructional practices predominantly centered on conventional teacher-directed approaches. This study aims to determine the effect of the Problem-Based Learning (PBL) model on improving IPAS learning outcomes among fifth-grade students at SD Kristen 1 Waimahu. The research method employed was a quasi-experimental design using a nonequivalent control group design. The study sample comprised 25 students selected through a total sampling technique, consisting of 13 students in the experimental class taught with the PBL model and 12 students in the control class taught using conventional learning. Data were gathered through an expert-validated multiple-choice achievement test and analyzed using descriptive statistics, the Shapiro-Wilk normality test, the Levene homogeneity test, the independent sample t-test, and the N-gain test. The results demonstrated that the posttest mean score of the experimental class (71.15) was considerably higher than that of the control class (45.83). The independent sample t-test yielded a significance value of 0.000 (< 0.05), verifying a statistically significant difference in learning outcomes between the two groups. Furthermore, the experimental class achieved an average N-gain score of 0.53 (moderate category), whereas the control class only attained 0.18 (low category). Consequently, the implementation of the Problem-Based Learning model exerts a positive and significant effect on enhancing elementary school students' IPAS learning outcomes. ABSTRAK Penelitian ini dilatarbelakangi oleh rendahnya hasil belajar Ilmu Pengetahuan Alam dan Sosial (IPAS) siswa kelas V di SD Kristen 1 Waimahu akibat proses pembelajaran yang masih didominasi pendekatan konvensional berpusat pada guru. Penelitian ini bertujuan untuk mengetahui pengaruh model Problem-Based Learning (PBL) terhadap peningkatan hasil belajar IPAS pada siswa kelas V di SD Kristen 1 Waimahu. Metode penelitian yang digunakan adalah eksperimen semu (quasi-experimental design) dengan rancangan nonequivalent control group design. Sampel penelitian berjumlah 25 siswa yang ditentukan melalui teknik sampling jenuh (total sampling), terbagi ke dalam kelas eksperimen sebanyak 13 siswa yang dibelajarkan dengan model PBL dan kelas kontrol sebanyak 12 siswa dengan pembelajaran konvensional. Data dikumpulkan melalui instrumen tes hasil belajar pilihan ganda yang telah divalidasi ahli, kemudian dianalisis menggunakan statistik deskriptif, uji normalitas Shapiro-Wilk, uji homogenitas Levene, uji independent sample t-test, dan uji N-gain. Hasil penelitian menunjukkan bahwa rata-rata nilai posttest kelas eksperimen (71,15) lebih tinggi dibandingkan kelas kontrol (45,83). Hasil uji independent sample t-test menghasilkan nilai signifikansi 0,000 (< 0,05) yang membuktikan adanya perbedaan hasil belajar secara signifikan antara kedua kelompok. Selain itu, nilai N-gain kelas eksperimen mencapai 0,53 (kategori sedang), sedangkan kelas kontrol hanya memperoleh 0,18 (kategori rendah). Dengan demikian, penerapan model Problem-Based Learning berpengaruh positif dan signifikan dalam meningkatkan hasil belajar IPAS siswa kelas V sekolah dasar. ]]>
