The Effectiveness of the Project-Based Learning Model in Indonesian Colonial Resistance Learning on Students’ Understanding of Indonesian Nationalism at Islamic High School Al-Asror Semarang

History learning plays an important role in instilling the values of nationalism in students. One of the factors influencing the success of this learning process is the use of instructional models that actively engage students. The Project-Based Learning (PJBL) model is considered an alternative approach that emphasizes student involvement through meaningful and contextual project activities. This study aims to examine the effectiveness of the Project-Based Learning model in improving students’ understanding of nationalism in history learning at Islamic High School Al-Asror Semarang. This study employed a quantitative approach using a quasi-experimental design. The research population consisted of all eleventh-grade students at Islamic High School Al-Asror Semarang. The sample comprised one class as the experimental group and one class as the control group, selected through random sampling. Data were collected using pretest and posttest instruments. Data analysis included normality and homogeneity tests as prerequisite analyses, followed by hypothesis testing using the Independent Samples t-test and N-Gain analysis to determine the level of learning effectiveness. The results showed that the experimental group achieved an average N-Gain score of 0.4424 (44.24%), while the control group obtained an average N-Gain scor70e of 0.3472 (34.72%). The results of the t-test indicated a significance value of 0.000 (< 0.05) with a mean difference of −16.300. These findings indicate that the Project-Based Learning model is more effective than conventional instruction in improving students’ understanding of Indonesian nationalism. Keywords: Nationalism Understanding, Project Based Learning, History Learning, Indonesian National Resistance