<![CDATA[ABSTRACTThis study employed a Classroom Action Research (CAR) design aimed at improving students’ learning outcomes through the implementation of the Project-Based Learning (PjBL) model in the circulatory system topic for eighth-grade students at SMP Negeri 18 Pontianak. The research was conducted in two cycles, each consisting of four stages: planning, action, observation, and reflection. The participants of this study were 33 students from class VIII A of SMP Negeri 18 Pontianak. The research instruments included learning devices, observation sheets for monitoring the implementation of learning activities, and learning outcome tests. All instruments were validated by five experts. Content validity was analyzed using Aiken’s V, while reliability was assessed using the Intraclass Correlation Coefficient (ICC). The results indicated that the research instruments met the criteria for validity, and the ICC analysis showed an acceptable level of reliability. The findings revealed that the implementation of learning activities improved from 85.71% in Cycle I to 100% in Cycle II. Furthermore, the mean learning outcome score increased from 76.67 in Cycle I to 85.76 in Cycle II, while the percentage of students achieving mastery learning improved from 84.85% to 100%. These results indicate that the implementation of the Project-Based Learning (PjBL) model in the circulatory system topic effectively improved the learning outcomes of eighth-grade students at SMP Negeri 18 Pontianak.Keywords: Circulatory System, Learning Outcomes, Project Based Learning. ABSTRAKPenelitian ini adalah Penelitian Tindakan Kelas (PTK) ditujukan untuk mengetahui peningkatan hasil belajar siswa melalui penerapan model pembelajaran Project Based Learning (PjBL) di materi sistem peredaran darah kelas VIII SMP Negeri 18 Pontianak. Penelitian dilaksanakan dalam 2 siklus dengan tahapan perencanaan, tindakan, observasi, dan refleksi. Subjek penelitian ini adalah 33 siswa kelas VIII A SMP Negeri 18 Pontianak. Instrumen penelitian berupa perangkat pembelajaran, lembar observasi pelaksanaan pembelajaran, dan tes hasil belajar. Instrumen divalidasi oleh 5 ahli dan validitas isi dianalisis menggunakan Aiken’s V dan diuji reliabilitas menggunakan Intraclass Correlation Coefficient (ICC). Hasil validasi isi instrumen penelitian dalam kategori valid dan hasil analisis reliabilitas ICC menunjukkan dalam kategori cukup. Hasil penelitian menunjukkan keterlaksanaan pembelajaran meningkat dari 85,71% pada siklus I menjadi 100% pada siklus II dan peningkatan dari rata-rata hasil belajar 76,67 pada siklus I menjadi 85,76 pada siklus II dengan persentase ketuntasan belajar meningkat dari 84,85% menjadi 100%. Hal ini menunjukkan bahwa penerapan model PjBL di materi sistem peredaran darah mampu meningkatkan hasil belajar siswa kelas VIII SMP Negeri 18 Pontianak. Kata Kunci: Hasil Belajar, Project Based Learning, Sistem Peredaran Darah.]]>
