<![CDATA[The learning outcomes of fourth-grade students at SD Negeri 2 Tiakur in measurement and unit conversion are still low because the learning process is still teacher-centered and does not provide enough hands-on experience for students. This study aims to improve student learning outcomes in measurement and unit conversion through the application of the Problem-Based Learning (PBL) model. The research used the Classroom Action Research (CAR) method, which was carried out in two cycles with 23 fourth-grade students as the research subjects. Each cycle consisted of the planning, implementation, observation, and reflection stages. Data collection techniques used tests, observation, and documentation. The data were analyzed quantitatively using the learning completeness percentage formula. The results showed an increase in student learning completeness from the pre-cycle to cycle II. In the pre-cycle, only 2 students (9%) were complete with an average score of 64. In cycle I, it increased to 10 students (43%) with an average of 70. In cycle II, completeness reached 21 students (91%) with an average of 80. Student activity also increased, as seen from their enthusiasm in asking questions, discussing, and solving problems. It can be concluded that the PBL model is effective in improving learning outcomes and student activity in measurement and unit conversion material in grade IV at SD Negeri 2 Tiakur. ABSTRAK Hasil belajar matematika siswa kelas IV SD Negeri 2 Tiakur pada materi pengukuran dan konversi satuan masih rendah karena pembelajaran yang masih berpusat pada guru dan kurang memberikan pengalaman langsung kepada siswa. Penelitian ini bertujuan untuk meningkatkan hasil belajar siswa pada materi pengukuran dan konversi satuan melalui penerapan model Problem Based Learning (PBL). Penelitian menggunakan metode Penelitian Tindakan Kelas (PTK) yang dilaksanakan dalam dua siklus dengan subjek penelitian 23 siswa kelas IV. Setiap siklus terdiri dari tahap perencanaan, pelaksanaan, pengamatan, dan refleksi. Teknik pengumpulan data menggunakan tes, observasi, dan dokumentasi. Data dianalisis secara kuantitatif menggunakan rumus persentase ketuntasan belajar. Hasil penelitian menunjukkan peningkatan ketuntasan belajar siswa dari pra siklus ke siklus II. Pada pra siklus, hanya 2 siswa (9%) yang tuntas dengan rata-rata nilai 64. Pada siklus I meningkat menjadi 10 siswa (43%) dengan rata-rata 70. Pada siklus II, ketuntasan mencapai 21 siswa (91%) dengan rata-rata 80. Aktivitas siswa juga meningkat, terlihat dari keaktifan bertanya, berdiskusi, dan menyelesaikan masalah. Dapat disimpulkan bahwa model PBL efektif meningkatkan hasil belajar dan aktivitas siswa pada materi pengukuran dan konversi satuan di kelas IV SD Negeri 2 Tiakur.]]>
