Model pembelajaran berbasis proyek (project based learning) merupakan model belajar yang melibatkan siswa secara langsung dalam memecahkan permasalahan menggunakan kegiatan proyek. melalui kegiatan proyek, siswa diberi kesempatan untuk aktif mengumpulkan dan mengintegrasikan pengetahuan baru berdasarkan pengalaman mereka dalam beraktifitas secara nyata. adapun penelitian ini bertujuan untuk mengetahui efektivitas model pembelajaran project based learning (pjbl) terhadap hasil belajar matematika siswa kelas v sdn 018 tarakan. penelitian ini menggunakan jenis penelitian kuantitatif dengan metode pre-eksperimental dalam kategori pre-experimental design one-group pretest-posttest. keberhasilan treatment ditentukan dengan membandingkan nilai pre-test dan nilai post-test. hasil analisis pretest menunjukkan nilai untuk signifikansi (sig) nya (0,200 > 0,05) dan nilai untuk posttest signifikansi (sig) nya (0,200 > 0,05). kesimpulannya sampel berasal dari populasi berdistribusi normal. berdasrkan hasil analisis uji t-test dengan menggunakan rumus paired sample t-test diperoleh hasil analisis bahwa nilai t = - 13,7016 dan signifikansi 0, 000 karena nilai signifikansi ( 2-tailed < 0,05 ) maka di simpulkan bahwa rata-rata hasil belajar matematika sebelum diterapkan model pembelajaran pjbl lebih kecil dibanding setelah di terapkan model pembelajaran pjbl. sementara untuk melihat efektivitasnya dilakukan analisis gain ternomalisasi (n - gain). dari hasil analisis rata-rata n - gain yang diperoleh nilai g 0,71 berada pada kategori tinggi dengan nilai n - gain persen = 71,4856 berada pada kriteria tafsiran cukup efektif. hal ini juga terlihat pada saat proses pembelajaran, siswa terlihat lebih aktif, lebih bersemangat serta minat dalam belajar meningkat. kata kunci: efektivitas, project based learning, hasil belajar

The project-based learning model is a learning model that involves students directly in solving problems using project activities. through project activities, students are given the opportunity to actively collect and integrate new knowledge based on their experiences in real activities. this research aimed to determine the effectiveness of the project-based learning (pjbl) model on mathematics learning achievement of the fifth-grade students of sdn 018 tarakan. this research employed a pre-experimental method with the one-group pretest-posttest design. the success of the treatment was determined by comparing the pretest and posttest scores. because the sample was derived from a normally distributed population, the t-test analysis was then determined using the parametric analysis, in this case, the paired sample t-test formula. the result of the pretest analysis showed the value of significance (sig.) was smaller than the level of significance (a) (0,200>0,05) but then the posttest showed the value of significance (sig) which was greater than the level of significance (a) (0,200>0,05). the result of the analysis also showed that the t-test value was - 13,7016 with a significance value of 0,000. because the significance value (2-tailed) < 0,05. it indicated that the mean score of mathematics learning achievement before the treatment using pjbl model increased significantly after the pjbl model was applied. meanwhile, to see its effectiveness, a normalized gain (n-gain) analysis was carried out. from the result of the average n-gain analysis, it was obtained that the value of g 0,71 was in high category with the percentage of n - gain 71,4856 which was in the criteria of a fairly effective interpretation. this result was also proven during the learning process, the students were observed to be more active and enthusiastic, and their interest in learning increased. keywords: effectiveness, project based learning, learning achievement