Abstract
This study addressed the low level of students’ critical thinking skills in Integrated Science and Social Studies (IPAS) learning among fourth-grade students at Madrasah Ibtidaiyah Negeri (MIN) Kudus, which was influenced by less supportive instructional methods and assessments focusing on lower-order cognitive skills. The study aimed to examine the effect of a Project-Based Learning–based teaching module using a simple terrarium project on students’ critical thinking skills. A quantitative quasi-experimental design with a non-equivalent control group was employed. The participants consisted of 54 fourth-grade students, with 27 students in the experimental class and 27 students in the control class, selected through purposive sampling. Data were collected using a validated and reliable critical thinking skills test administered as pretest and posttest. Data analysis included paired sample t-tests and independent sample t-tests. The findings revealed a significant improvement in students’ critical thinking skills in the experimental group compared to the control group. The experimental group achieved higher mean percentages across all indicators, namely elementary clarification (84.6%), basic support (96.3%), inference (80.6%), advanced clarification (86.1%), and strategies and tactics (77.3%), while the control group obtained lower results (46.9%, 68.5%, 62.3%, 42.6%, and 39.8%, respectively). The paired sample t-test indicated a significant increase in the experimental group (p = 0.000; mean difference = −25.259), whereas the control group showed a smaller improvement (p = 0.013; mean difference = 4.148). Furthermore, the independent sample t-test confirmed a significant difference between the two groups (p = 0.000; mean difference = 32.000). These results demonstrate that Project-Based Learning–based teaching modules using simple terrarium projects effectively enhance elementary students’ critical thinking skills in IPAS learning.