<![CDATA[This study is aimed to determine the effect of science process skills approach to rational thinking ability of students. The study design was a pretest-posttest design non-equivalent groups. The samples in this study were class X1 and X2 that selected by purposive sampling technique. The quantitative data obtained from pretest and posttest values were analyzed by comparison of N-gain using a Hake formula, while the qualitative data in the form of student learning activity data were analyzed descriptively. The results of study indicated that the application of science process skills approach can improve students' ability to think rationally (N-gain 63,53). The ability of students from each observed indicators of rational thinking has increased. The highest enhancement was an indicator of the ability to gather information and the lowest is the ability to solve problems rationally. Thus the application of science process skills approach gave significant effect in improving rational thinking ability and student learning activities. Penelitian ini bertujuan untuk mengetahui pengaruh pendekatan keterampilan proses sains terhadap kemampuan berpikir rasional siswa. Desain penelitian adalah desain pretes-postes kelompok non equivalen. Sampel penelitian ini adalah siswa kelas X1 dan X2 yang dipilih dengan teknik purposive sampling. Data kuantitatif diperoleh dari nilai pretes dan postes yang dianalisis dengan perbandingan N-gain menggunakan formula Hake, sedangkan data kualitatif berupa data aktivitas belajar siswa yang dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa penerapan pendekatan keterampilan proses sains dapat meningkatkan kemampuan berpikir rasional siswa (N-gain 63,53). Kemampuan siswa dari tiap indikator berpikir rasional yang diamati mengalami peningkatan. Peningkatan tertinggi adalah indikator kemampuan menggali informasi dan terendah adalah kemampuan memecahkan masalah secara rasional. Dengan demikian penerapan pendekatan keterampilan proses sains berpengaruh signifikan dalam meningkatkan kemampuan berpikir rasional dan aktivitas belajar siswa.Kata kunci: aktivitas belajar siswa, keterampilan berpikir rasional, keterampilan proses sains]]>
