<![CDATA[Natural and Social Sciences (IPAS) learning in elementary schools frequently encounters instructional constraints due to the dominance of conventional lecture methods that neglect individual accountability in collaborative tasks. The limited exploration of structured cooperative learning models regarding the topic of natural environmental changes has contributed to students' suboptimal conceptual understanding. This study aims to determine students' learning outcomes before and after being taught using the Numbered Head Together (NHT) model and to examine the significance of its effect on the IPAS learning outcomes of fifth-grade students at UPT SD Negeri 064991 Medan Amplas in the 2025/2026 academic year. A quantitative pre-experimental method using a one-group pretest-posttest design was employed. The research sample was determined using a total sampling technique involving all 21 fifth-grade students in class V-A. Data were gathered through validated written achievement tests, student response questionnaires, observation sheets, and documentation. Data analysis was conducted using descriptive statistics, the Shapiro-Wilk normality test, and the paired sample t-test. The findings revealed that the students' average pretest score of 43.04 significantly increased to 76.52 in the posttest. The paired sample t-test yielded a t_"count" value of -19.442 with a significance value of p=0.000<0.05, confirming a statistically significant difference in learning outcomes following the intervention. Consequently, the implementation of the Numbered Head Together (NHT) learning model exerts a positive and statistically significant effect on elementary school students' IPAS learning outcomes. ABSTRAK Pembelajaran Ilmu Pengetahuan Alam dan Sosial (IPAS) di sekolah dasar kerap mengalami kendala akibat dominasi metode ceramah konvensional yang belum mengoptimalkan tanggung jawab individual dalam kerja kelompok. Keterbatasan eksplorasi model pembelajaran kooperatif terstruktur pada materi perubahan kondisi alam menyebabkan rendahnya pemahaman konsep siswa. Penelitian ini bertujuan untuk mengetahui hasil belajar siswa sebelum dan sesudah diajarkan menggunakan model pembelajaran Numbered Head Together (NHT) serta menguji signifikansi pengaruhnya terhadap hasil belajar IPAS siswa kelas V UPT SD Negeri 064991 Medan Amplas Tahun Ajaran 2025/2026. Jenis penelitian yang digunakan adalah penelitian kuantitatif dengan pendekatan pra-eksperimental (pre-experimental design) melalui rancangan one-group pretest-posttest design. Sampel penelitian ditentukan menggunakan teknik sampling jenuh yang melibatkan seluruh anggota populasi siswa kelas V-A sebanyak 21 orang. Pengumpulan data dilakukan melalui instrumen tes tertulis, angket respons, lembar observasi keterlaksanaan, dan dokumentasi yang telah teruji validitas dan reliabilitasnya. Data dianalisis secara bertahap melalui statistik deskriptif, uji normalitas Shapiro-Wilk, serta uji hipotesis menggunakan paired sample t-test. Hasil penelitian menunjukkan bahwa nilai rata-rata pretest peserta didik sebelum perlakuan sebesar 43,04 meningkat secara signifikan menjadi 76,52 pada saat posttest. Hasil pengujian hipotesis menggunakan paired sample t-test menghasilkan nilai t_"hitung" =-19,442 dengan nilai signifikansi p=0,000<0,05, membuktikan adanya perbedaan kemampuan kognitif yang signifikan pascaperlakuan. Dengan demikian, penerapan model pembelajaran Numbered Head Together (NHT) terbukti berpengaruh positif dan signifikan terhadap peningkatan hasil belajar IPAS siswa sekolah dasar. ]]>
