<p class="Abstract">The aims of this study was to test the effectiveness of the Relating, Experiencing, Applying, Cooperating, Transferring (REACT) learning model in improving students' understanding of physics concepts. This research used Action Research with the research subjects of class X MIPA 4 SMA N 2 Batang. Data collection techniques using tests. The results of the research in cycle I showed the number of students who got a score of ≥ 60 was 4 students and cycle II was 14 students. These results indicate that the REACT learning model can improve students' understanding of physics concepts. The learning process that is carried out is always connected with events that occur in real life so that students understand the concept more deeply. The REACT learning model can be applied to other physics materials so that students are more actively involved in learning and improve students' understanding of physics concepts.</p>

ABSTRAKPrestasi belajar siswa ditunjukkan berdasarkan hasil observasi awal menunjukkan bahwa pembelajaran yang dilakukan belum berjalan secara maksimal.Oleh karena itu untuk meningkatkan prestasi belajar siswa diperlukan model pembelajaran dengan model dan strategi yang tepat. Salah satunya adalah model pembelajaran Problem Solving Penelitian ini bertujuan untuk meningkatkan prestasi belajar siswa. Lokasi penelitian ini di SMA Negeri 1 Denpasar dengan jumlah siswa 46 orang. Data dalam penelitian ini diperoleh dari tes prestasi belajar yang kemudian dilakukan analisis secara deskriptif.Penelitian ini dilaksanakan dalam dua siklus. Setiap siklus dilakukan berdasar tahapan: (1) menyusun rencana kegiatan, (2) melaksanakan tindakan,(3) observasi, dan (4) refleksi.Hasil penelitian menunjukkan bahwa menurut hasil observasi awal pembelajaran siswa kurang aktif, mudah jenuh, dan perhatian siswa pada penjelasan guru sangat kecil sehingga nilai ratarata siswa hanya sebesar 72.97. Setelah tindakan siklus I penguasaan materi pembelajaran meningkat menjadi rata-rata 78,24 dengan siswa tuntas 27 siswa dan belum tuntas 10 siswa. Hasil tindakan pada siklus II penguasan materi setelah diberikan tes prestasi belajar meningkat menjadi rata-rata 84,19 dengan siswa tuntas 35 orang dan 2 orang siswa belum tuntas. Presentase ketuntasan belajar pada siklus II ini telah memenuhi indikator keberhasilan yang ditetapkan dan siklus dinyatakan tidak dilanjutkan,dengan kesimpulan bahwa pemanfaatan model pembelajaran Problem Solving telah mampu dengan baik untuk dijadikan alternatif dalam meningkatkan prestasi belajar siswa. Kata Kunci : Model Pembelajaran Problem Solving dan Prestasi Belajar Fisika Siswa.ABSTRACT Student achievement is shown by the results of the initial observations indicate that learning is done not run maXI-MIAmum. Therefore to improve student achievement required learning model with the model and the right strategy. One is the learning model of Problem Solving This study aims to improve student achievement. The location of this research at SMA Negeri 1 Denpasar with the number of students 46 people. The data in this study were obtained from the learning achievement test which is then carried deskriptif. The research analysis was conducted in two cycles. Each cycle is done based on the following steps: ( 1 ) develop a plan of activities, ( 2 ) carry out actions , ( 3 ) observation, and ( 4 ) refleksi. The result of research shows that according to the preliminary observations of student learning outcomes are less active, easily bored, and the students' attention on teacher's explanation is so small that the average value of 72.97 students only. After the first cycle measures mastery learning materials increased to an average of 78,24 with 27 students and the students completed the unfinished 10 students . The results of the action in the second cycle after the material mastery learning achievement test given rise to an average of 84.19 with 35 students completed and unfinished 2 students. Percentage of mastery learning in th...