摘要：Penelitian ini bertujuan untuk mendeskripsikan keefektifan model pembelajaran kooperatif tipe Student Teams-Achievement Divisions (STAD) dan Team-Assisted Individualization (TAI) dalam pendekatan penemuan terbimbing pada materi bangun ruang sisi datar ditinjau dari prestasi belajar, kemampuan berpikir kritis, dan kepercayaan diri siswa, dan membandingkan keefektifan antara kedua model pembelajaran tersebut. Penelitian ini merupakan penelitian eksperimen semu. Populasi mencakup seluruh siswa kelas VIII SMP Negeri 11 Yogyakarta dan sampel diambil dua kelas secara acak dari 4 kelas yang ada. Analisis univariat dengan statistik uji one sample t-test dan uji paired sample t test pada taraf signifikansi 5% dilakukan untuk menguji keefektifaan model pembelajaran. Uji Multivariat Analysis of Variance (MANOVA) dilakukan untuk membandingkan keefektifaan kedua model pembelajaran. Hasil penelitian menunjukkan bahwa model pembelajaran kooperatif tipe STAD dan TAI dalam pendekatan penemuan terbimbing pada materi bangun ruang sisi datar masing-masing efektif ditinjau dari ketiga variabel terikat. Hasil penelitian juga menunjukkan bahwa terdapat perbedaan signifikan prestasi belajar dan kemampuan berpikir kritis antara kelompok model pembelajaran kooperatif tipe STAD dan TAI, namun tidak terdapat perbedaan signifikan jika ditinjau dari kepercayaan diri siswa. Cooperative learning using a guided discovery approach viewed from the learning achievement, critical thinking ability, and self-confidence Abstract This study aimed to describe the effectiveness of the cooperative learning model of Student Teams-Achievement Divisions (STAD) and Team-Assisted Individualization (TAI) types using the guided discovery approach in learning polyhedra viewed from the learning achievement, critical thinking ability, and self-confidence of the students, and compare the effectiveness of both learning models. This study was quasi-experimental. The research population comprised four classes of eighth-grade students of SMP Negeri 11 (Junior High School) in Yogyakarta, Indonesia and the sample of two classes was established randomly from the four classes. Univariate analysis with statistical one-sample t-test and paired sample t-test at a significance level of 5% was carried out to test the effectiveness of the learning model. The Multivariate Analysis of Variance (MANOVA) test was performed to compare the effectiveness of the two learning models. The results showed that the cooperative learning model of STAD and TAI types using the guided discovery approach on the material of polyhedra respectively effective in terms of the three dependent variables. The results also showed that there were significant differences in learning achievement and critical thinking skills between the cooperative learning model of STAD and TAI types groups, but there were no significant differences in terms of students’ self-confidence.
