The aim of this study is to determine whether the Student Teams Achievement Divisions method, which is included in the cooperative learning model, has any effect on the problem-solving skills of the students. The research was carried out in accordance with the quasi-experimental model with the control group, and the research data were obtained by using a mixed research design in which quantitative and qualitative research methods were used together. The application was conducted at the seventh grade level. Research data were collected via module tests, academic achievement tests, student worksheets, and preliminary knowledge tests. The research was car- ried out in three stages in seventh graders. In the first stage, the problem squats prepared on the subjects that the seventh grade students had seen in the fifth and sixth grades were applied. In the second stage, problem-solving worksheets prepared on the topics covered in the fall semes- ter science course of the seventh graders were applied. In the third stage, problem-solving work- sheets prepared on eighth grade subjects that seventh grade students did not see were applied. Student Teams Achievement Divisions method was applied to the experimental group, and the current teaching method carried out in accordance with the curriculum was applied to the con- trol group. The data were analyzed using quantitative and qualitative analysis methods. According to the findings obtained in the study, it was determined that the experimental group’s average scores in the problem-solving worksheets, module tests, and academic achievement tests were significantly higher than the control group.