<![CDATA[Abstrak Penelitian ini bertujuan untuk menganalisis peningkatan kemampuan representasi matematis siswa melalui penerapan model Problem Based Learning (PBL) berbasis STEM pada materi fungsi dan grafik. Penelitian menggunakan pendekatan kuantitatif dengan desain quasi experiment tipe one-group pretest-posttest design. Sampel penelitian terdiri atas 31 siswa kelas X SMA Negeri 1 Percut Sei Tuan yang dipilih menggunakan teknik purposive sampling. Pengumpulan data dilakukan melalui tes kemampuan representasi matematis, observasi, wawancara, dan dokumentasi. Hasil penelitian menunjukkan adanya peningkatan kemampuan representasi matematis siswa, ditunjukkan oleh rata-rata nilai pretest sebesar 2,355 yang meningkat menjadi 3,625 pada posttest. Hasil uji N-Gain memperoleh nilai rata-rata sebesar 0,784 dengan kategori tinggi. Temuan tersebut menunjukkan bahwa model PBL berbasis STEM efektif dalam meningkatkan kemampuan representasi matematis siswa pada materi fungsi dan grafik. Kata Kunci: Problem Based Learning, STEM, Kemampuan Representasi Matematis Abstract This study aimed to analyze the improvement of students’ mathematical representation abilities through the implementation of a STEM-based Problem Based Learning (PBL) model on function and graph material. The study employed a quantitative approach using a quasi-experimental method with a one-group pretest-posttest design. The sample consisted of 31 tenth-grade students at SMA Negeri 1 Percut Sei Tuan selected through purposive sampling. Data were collected through mathematical representation ability tests, observations, interviews, and documentation. The results indicated an improvement in students’ mathematical representation abilities, as shown by the increase in the average pretest score from 2.355 to 3.625 in the posttest. Furthermore, the N-Gain test result showed an average score of 0.784, categorized as high. These findings indicate that the STEM-based PBL model is effective in improving students’ mathematical representation abilities in function and graph material. Keywords: Problem Based Learning, STEM, Mathematical Representation Ability]]>
