<![CDATA[This experimental research aimed to find out the effectiveness of contextual teaching and learning (CTL) in terms of students mathematical reasoning skill. The population of this research was all VII grade students of Junior High School state of 3 Natar in academic year of 2017/2018 which were distributed into ten classes. The samples of this research were students of VIII E and VIII F class which were chosen by purposive random sampling. This research used pretest-posttest control group design. The data of students mathematical reasoning skill were obtained by essay test. The data analysis of this research used Mann-Whitney U test. Based on the research, it was concluded that CTL was not effective in terms of students mathematical reasoning skill.Penelitian ini bertujuan untuk mengetahui efektivitas contextual teaching and learning (CTL) ditinjau dari kemampuan penalaran matematis siswa. Populasi pada penelitian ini adalah seluruh siswa kelas VII SMP Negeri 3 Natar tahun pelajaran 2017/2018 yang terdistribusi dalam sepuluh kelas. Sampel pada penelitian ini adalah siswa kelas VII E dan VII F yang dipilih dengan teknik purposive random sampling. Penelitian ini menggunakan pretest-posttest control group design. Data kemampuan penalaran matematis siswa diperoleh dari tes yang berbentuk uraian. Analisis data pada penelitian ini menggunakan uji Mann-Whitney U. Berdasarkan hasil penelitian dan pembahasan diperoleh kesimpulan bahwa CTL tidak efektif ditinjau dari kemampuan penalaran matematis.Kata kunci: contextual teaching and learning, efektivitas, penalaran matematis siswa]]>
