Abstract

Previous research has designed textbooks to use to provide support learning in the Merdeka curriculum on atomic structure material, which have been tested for validity and practicality, but have not yet been tested for effectiveness. The purpose of this study was for identification purposes how well textbooks that support student learning in the free curriculum on atomic structure material affect their learning outcomes. This quasi-experimental research is a continuation of research on Plomp's development model. This study was conducted using a pretest posttest nonequivalent control group design. The study involved 71 students in two groups, an experimental class and a control class. The results showed that the experimental class had an average N-gain value of 0.75 in the high category, and the control class had an average N-gain value of 0.65 in the medium category. The calculated t value of 9.43 and t table of 1.99 were found in hypothesis testing with t-test. The data analysis indicated that the textbooks used to teach atomic structure in the free curriculum may have contributed to improved learning outcomes for students.