<![CDATA[ABSTRACT Limitations in conceptual understanding of mathematics at the elementary school level highlight the importance of active problem-oriented learning strategies. This study aims to examine whether there is a significant difference in mathematics learning outcomes between third-grade students receiving Problem Based Learning (PBL) instruction and those following conventional learning on time-unit measurement at SD Negeri 1 Banyuasin I. Quantitative evidence was established through a quasi-experimental approach employing a posttest-only control group design. Sample selection involved 53 students divided via random sampling into class III C with 26 students as the intervention group and class III B with 27 students as the control group. Learning achievement was assessed using essay tests verified for validity and reliability, followed by data processing through normality, homogeneity, and Independent Sample t-Test procedures. The mean posttest score for the experimental group reached 82.4, exceeding the control group's average of 69.7. Inferential results revealed a two-tailed significance value of p < 0.001 along with a calculated t-value of 10.036, which surpassed the critical t-value of 2.000. These findings confirm the efficacy of PBL intervention in driving differences in mathematics achievement on time-measurement concepts. ABSTRAK Keterbatasan pemahaman konseptual matematika di tingkat sekolah dasar menegaskan pentingnya orientasi pembelajaran berbasis eksplorasi masalah secara aktif. Kajian ini difokuskan untuk menguji ada tidaknya perbedaan signifikan pada hasil belajar matematika antara siswa yang mendapatkan instruksi berbasis Problem Based Learning (PBL) dan siswa yang mengikuti pembelajaran konvensional pada materi pengukuran satuan waktu di kelas III SD Negeri 1 Banyuasin I. Pembuktian kuantitatif dijalankan melalui skema quasi-experiment memakai desain posttest-only control group design. Penentuan sampel melibatkan 53 peserta didik yang terbagi secara random sampling ke dalam kelas III C sejumlah 26 anak sebagai kelompok intervensi dan kelas III B sebanyak 27 anak selaku kelompok pembanding. Pengukuran capaian belajar menggunakan tes uraian yang telah teruji validitas serta reliabilitasnya, dilanjutkan pengolahan data melalui uji prasyarat normalitas, homogenitas, hingga pengujian komparatif Independent Sample t-Test. Perolehan skor rerata posttest kelompok eksperimen sebesar 82,4 terbukti melampaui kelompok kontrol yang memperoleh angka 69,7. Bukti inferensial mencatatkan signifikansi dua arah ( ) < 0,001 serta perolehan hitung sebesar 10,036 yang melampaui tabel sebesar 2,000. Temuan ini mengonfirmasi efikasi intervensi PBL dalam memicu diferensiasi capaian belajar matematika pada topik satuan waktu.]]>
