The purpose of this study is to demonstrate that performance assessment increases educational value in teaching-learning activities using a quasi-experimental research design. In this research, the three measurement criteria of educational value are suggested as "improvement & advancement," "sincerity & enthusiasm," and "individuality & wholeness." A pre-test was administered to 4 classes (156 students) in 7th grade. Classes were divided into an experimental group (2 classes, 79 students) and a control group (2 classes, 77 students), according to the pre-test results. Only the experimental group was involved in the performance assessment for 9 weeks. The results of this study show that performance assessment has a positive effect on the educational value of teaching-learning activities in schools.