<![CDATA[AbstrakMasalah dalam penelitian ini adalah pemilihan model pembelajaran yang digunakan guru belum bervariasi, siswa kurang aktif ketika berlangsungnya kegiatan belajar mengajar, daya serap siswa rendah, guru menyajikan materi dengan metode konvensional, sehingga siswa kurang faham dan prestasi rendah. Tujuan penelitan ini adalah untuk mengetahui komunikasi matematis siswa melalui KBM dengan model problem based learning (PBL) di kelas XI SMA Swasta Kartika 1-4 Pematangsiantar. Metode penelitian adalah metode quasi-experimental design dengan jenis two group randomized posttest-only control design. Teknik pengambilan sampel dengan sampling purposive dan hipotesis dengan uji t pada tingkat kepercayaan α = 0,05. Dari analisis penelitian, diperoleh 1) Komunikasi matematis siswa dengan model problem based learning lebih baik daripada komunikasi matematis siswa dengan metode konvensional; 2) Terdapat peningkatan komunikasi matematis siswa yang menggunakan model problem based; dan 3) Terdapat Sikap positif siswa terhadap pembelajaran dengan menggunakan model pembelajaran problem based learning. Kata kunci: Problem based learning, Komunikasi matematis, Quasi-experimental design Abstract The problem in this study is that the selection of learning models used by teachers has not varied, students are less active when teaching and learning take place, students' absorption is low, and teachers present material using conventional methods, so students lack understanding and low achievement. The purpose of this research is to find out students' mathematical communication through KBM with the PBL model in class XI SMA Swasta Kartika 1-4 Pematangsiantar. The research method is a quasi-experimental design with a two-group randomized posttest-only control design. Sampling technique with purposive sampling, Hypothesis with t-test at the confidence level α = 0.05. From the research analysis, it was obtained 1) Students' mathematical communication using the problem-based learning model was better than students' mathematical communication using conventional methods; 2) There is an increase in students' mathematical communication using problem-based models, and 3) there is a positive attitude of students towardslearning by using the problem-based learning model. Keywords: Problem based learning, Mathematic Communication, Quasi-experimental design]]>
