The purpose of this study is to investigate whether there is a significant effect of project based learning approach on seventh grade students' academic achievement in the structure and properties of matter. In the study, according to the characteristics of quantitative research methods, pretest-posttest control group quasi-experimental design was used to test the effect of project-based learning and traditional methods on seventh grade students' academic achievement. Convenience sampling was preferred and 38 students participated in this study. The structure and properties of matter achievement test, lesson plans, and observation checklist were used as data collection instruments. In order to analyze the data obtained from the structure and properties of matter achievement test, independent samples t-test was performed. Based on the results, there is no significant difference between the experimental and control groups' scores which is obtained from their "Achievement test" post-test performance. Discussions based on literature were carried out and suggestions were performed as pre-activities based on project based learning should be performed for the adaptation of students and teachers before treatment.