Electronic Theses and Dissertation

Pendidikan abad ke-21 menuntut penguasaan kompetensi 4C, salah satunya
kemampuan berpikir kritis. Namun, kemampuan ini masih rendah karena
pembelajaran di sekolah cenderung masih didominasi oleh guru dan kurang
melibatkan siswa secara aktif. Penelitian ini bertujuan menguji efektivitas model
Problem Based Learning (PBL) berbasis Science, Technology, Engineering, and
Mathematics (STEM) dalam meningkatkan kemampuan berpikir kritis siswa pada
materi asam-basa. Penelitian menggunakan metode kuasi eksperimen dengan
desain pretest-posttest control group. Subjek penelitian adalah dua kelas XI Fase F
SMAN 1 Langsa yang dipilih melalui purposive sampling. Kelas eksperimen
menerapkan PBL berbasis STEM, sedangkan kelas kontrol menggunakan
Discovery Learning. Instrumen penelitian berupa tes uraian kemampuan berpikir
kritis dan lembar observasi aktivitas pembelajaran yang telah melalui uji kualitas
instrumen, meliputi uji validitas dan reliabilitas. Data hasil penelitian dianalisis
menggunakan uji N-gain untuk mengetahui peningkatan kemampuan berpikir
kritis, dilanjutkan dengan uji t untuk melihat perbedaan hasil antara kelas
eksperimen dan kelas kontrol setelah memenuhi uji prasyarat normalitas dan
homogenitas. Hasil penelitian menunjukkan peningkatan signifikan kemampuan
berpikir kritis siswa. Nilai N-gain kelas eksperimen sebesar 0,77 (kategori tinggi)
dan kelas kontrol 0,52 (kategori sedang). Uji t menunjukkan adanya perbedaan
signifikan antara kedua kelompok. Dengan demikian, model PBL berbasis STEM
efektif meningkatkan kemampuan berpikir kritis siswa pada materi asam-basa.
Kata Kunci: Problem Based Learning, STEM, Berpikir Kritis, Asam Basa

The 21st-century education demands mastery of 4C competencies, one of which is critical thinking skills. However, these skills remain relatively low because classroom learning is still dominated by teachers and lacks active student engagement. This study aims to examine the effectiveness of the Problem Based Learning (PBL) model based on the Science, Technology, Engineering, and Mathematics (STEM) approach in improving students’ critical thinking skills on acid–base material. This research employed a quasiexperimental method with a pretest–posttest control group design. The subjects were two eleventh-grade classes (Phase F) at SMAN 1 Langsa, selected through purposive sampling. The experimental class implemented the STEM-based PBL model, while the control class used the Discovery Learning model. The research instruments consisted of a critical thinking essay test and observation sheets of learning activities, both of which had passed instrument quality tests, including validity and reliability testing. Data were analyzed using the N-gain test to measure the improvement in students’ critical thinking skills, followed by a t-test to determine the differences between the experimental and control classes after fulfilling the normality and homogeneity assumptions. The results showed a significant improvement in students’ critical thinking skills. The Ngain value for the experimental class was 0.77 (high category), while the control class obtained 0.52 (moderate category). The t-test confirmed a significant difference between the two groups. Therefore, the STEM-based PBL model is effective in enhancing students’ critical thinking skills on acid– base material. Keywords: Problem Based Learning, STEM, Critical Thinking, Acids and Bases