This study aims: (1) to describe the effectiveness of Team Assisted Individualization (TAI) type of cooperative learning model and scientific approach in terms of learning achievement and self efficacy, (2) comparing the effectiveness of Team Assisted Individualization (TAI) type of cooperative learning model and scientific approach in terms of learning achievement and self efficacy. The type of research used is quasi experimental research. The population in this study were class VII students of SMP Negeri 2 Depok. Data were analyzed descriptively, hypothesis testing using one-sample t-test, MANOVA test with T 2 Hotteling formula. The results of the study are as follows. (1) The implementation of effective Team Assisted Individualization (TAI) type of cooperative learning model, while the scientific approach is not effective in terms of learning achievement and self efficacy. (2) The application of the Team Assisted Individualization (TAI) type of cooperative learning model is more effective than the application of the scientific approach.

This research aims to identify the student's error in the completion of real analysis using Newman Error Analysis (NEA). The type of research is qualitative descriptive. Which research subjects were 22 students of the mathematics education study program of Universitas Negeri Gorontalo at VI semesters in the 2020/2021 academic year. Data-collection techniques using written tests and interviews. Data is analyzed with reduction, presentation, and drawing conclusion. The result of the study found 4 errors made by students in answering a problem based on NEA: (1) reading, (2) comprehension, (3) transformation, (4) and process skills. This identification can be used by lecturers teaching real analysis to consider supporting the courses and designing learning systems to minimize student errors in solving problems.

This study aims to determine the distribution of student geometry levels based on Van Hiele's theory and find out the differences in students' mathematics learning outcomes in grade VII junior high school. The sampling technique is probability sampling and a sample of 182 students is obtained. Data collection techniques used were Van Hiele level geometry tests and test results. Data analysis used descriptive statistics and anova with a significance level of 5%. The results showed that only 170 students were included in the Van Hiele geometry level, namely 62 students were at level 0, 97 students were at level 1, 5 students were at level 2, and as many as 6 students are at level 3. In the inferential analysis based on analysis of variance (two-way anova) concludes that for learning outcomes based on Van Hiele level geometry obtained Fcount = 13.793 > Ftable = 9.28 means H0 is rejected means that there are differences in mathematics learning outcomes based on Van Hiele geometry level.AbstrakPenelitian ini bertujuan untuk mengetahui distribusi level geometri siswa berdasarkan teori Van Hiele dan mengetahui perbedaan hasil belajar matematika siswa di kelas VII SMP. Menggunakan teknik probability sampling dan diperoleh sampel sebanyak 182 siswa. Teknik pengumpulan data yang digunakan adalah tes level geometri Van Hiele dan tes hasil belajar. Analisis data menggunakan statistik deskriptif dan anova dengan taraf signifikansi sebesar 5%. Hasil analisis data menunjukkan bahwa dari 182 sampel, hanya 170 siswa yang termasuk dalam level geometri Van Hiele yaitu 62 siswa berada pada level 0, sebanyak 97 siswa pada level 1, sebanyak 5 siswa pada level 2, dan  6 siswa pada level 3. Analisis anova dua arah diperoleh Fhitung = 13,793 > Ftabel = 9,28 berarti H0  ditolak yang artinya terdapat perbedaan hasil belajar matematika berdasarkan level geometri Van Hiele.

The purpose of this study was to describe and identify students' level of thinking in doing questions based on Van Hiele's theory and to give an idea to teachers to be able to use learning methods in accordance with Van Hiele's level of thinking at IBNU Abbas Tarakan IT Junior High School. The method used in this research is a combination method (qualitative & qualitative) with sequential model. The research instruments used were tests on Van Hiele's geometry levels, and interview guidelines. Based on the results of the study obtained 3 students were in pre visualization or have not reached Van Hiele's thinking level, 6 students are at level 1 (visualization), 9 students are at level 2 (analysis), and 3 students are at level 3 (informal deduction). Based on interviews students still have difficulty in understanding the relationship between wakes as well as elements in geometry such as theorem, axiom, and definition. In conclusion, Van Hiele's geometry thinking level at Ibnu Abbas IT Junior High School is generally at level 2, namely the analysis stage and has not reached level 4 (informal deduction). Keywords: Geometry, Level of thinking, Van Hiele Theory

This study aims to determine the distribution of student geometry levels based on Van Hiele's theory and find out the differences in students' mathematics learning outcomes in grade VII junior high school. The sampling technique is probability sampling and a sample of 182 students is obtained. Data collection techniques used were Van Hiele level geometry tests and test results. Data analysis used descriptive statistics and anova with a significance level of 5%. The results showed that only 170 students were included in the Van Hiele geometry level, namely 62 students were at level 0, 97 students were at level 1, 5 students were at level 2, and as many as 6 students are at level 3. In the inferential analysis based on analysis of variance (two-way anova) concludes that for learning outcomes based on Van Hiele level geometry obtained Fcount = 13.793 > Ftable = 9.28 means H0 is rejected means that there are differences in mathematics learning outcomes based on Van Hiele geometry level.AbstrakPenelitian ini bertujuan untuk mengetahui distribusi level geometri siswa berdasarkan teori Van Hiele dan mengetahui perbedaan hasil belajar matematika siswa di kelas VII SMP. Menggunakan teknik probability sampling dan diperoleh sampel sebanyak 182 siswa. Teknik pengumpulan data yang digunakan adalah tes level geometri Van Hiele dan tes hasil belajar. Analisis data menggunakan statistik deskriptif dan anova dengan taraf signifikansi sebesar 5%. Hasil analisis data menunjukkan bahwa dari 182 sampel, hanya 170 siswa yang termasuk dalam level geometri Van Hiele yaitu 62 siswa berada pada level 0, sebanyak 97 siswa pada level 1, sebanyak 5 siswa pada level 2, dan  6 siswa pada level 3. Analisis anova dua arah diperoleh Fhitung = 13,793 > Ftabel = 9,28 berarti H0  ditolak yang artinya terdapat perbedaan hasil belajar matematika berdasarkan level geometri Van Hiele.