PENERAPAN MODEL PEMBELAJARAN PROBLEM BASED LEARNING PADA MATERI SISTEM IMUN UNTUK MENINGKATKAN KETERAMPILAN BERPIKIR KRITIS SISWA KELAS XI ? DI SMAN 1 TOJO

Critical thinking skills are among the essential 21st-century skills for students. However, observations in class XI B at SMAN 1 Tojo revealed that the learning process was still dominated by the lecture method, resulting in students' critical thinking skills not developing optimally. This study aimed to enhance students' critical thinking skills through the implementation of the Problem-Based Learning (PBL) model in the study of the immune system. A classroom action research (CAR) design was employed, conducted over two cycles. The research subjects were 28 students from class XI B at SMAN 1 Tojo. Data were collected
using teacher activity observation sheets and critical thinking skills tests covering the indicators of interpretation, analysis, evaluation, and inference. The data were analyzed using percentage techniques. The research results indicate that teacher activity increased from 88.16% in Cycle I to 94.16% in Cycle II, falling into the