In the 21st century, the world is experiencing development and change in every aspect of life, including education. This has resulted in the emergence of 21st-century learning, such as critical thinking skills. The urgency of critical thinking skills to analyze, solve, and evaluate various problems and decision-making is crucial for students. Teachers can improve students' critical thinking skills through learning. One of the strategies that can be pursued is to implement differentiated learning.
The low critical thinking skills of MTs Darul Ulum Semarang students are caused by several things, such as the material delivered only using lectures. The purpose of this study is to determine the effectiveness of differentiated learning to improve students' critical thinking skills. The approach of this research is quantitative in the form of quasi-experimental. The collected data was obtained using a nonequivalent control group design through pretest and posttest. The research sample of the experimental class is IX A, while the control class is IX B, which each totals 24 students. The data analysis technique was carried out through an N-gain and independent sample t-test reviewed from the results of the posttest of the experimental class and the control class. The results of the study revealed that the average posttest of the experimental class was 87 while the control class was 73. The n-Gain value of the experimental class was 0.6075, which showed a moderate increase, while the control class was 0.2490, which showed a low increase.
In addition, the tcount obtained is 5.201 where the tcount > ttable (5.201 > 2.012) and the P value is 0.000 where 0.000 < 0.05, then Ha is accepted. Therefore, the conclusion of this study is that between the experimental class and the control class, there is a significant difference in the average posttest, meaning that differentiated learning is effective in improving critical thinking skills in fiqh subjects at MTs Darul Ulum Semarang. Therefore, teachers can make differentiated learning an effective alternative to improve students' critical thinking skills.