Implementation of Problem-Based Learning to Enhance Students’ Critical-Thinking Activities in Chemistry Learning: A Classroom Action Research at SMAN 1 Pancung Soal

Anisa Rahmawati (Universitas Negeri Padang)
Desy Kurniawati (Universitas Negeri Padang)
Fauzana Gazali (Universitas Negeri Padang)

SEARCH: Science Education Research
Vol. 5 No. 1 (2026): SEARCH: October 2026

Critical thinking is a crucial skill in chemistry education as it supports students' abilities to analyze, evaluate, and solve problems logically, and it is commonly fostered through learning activities such as questioning, discussion, and collaborative problem-solving. Preliminary observations revealed that the majority of Grade XI (Phase F) students at SMAN 1 Pancung Soal demonstrated low levels of engagement in discussions, questioning, and the analysis of contextual chemistry problems. This situation highlights the need for a learning model capable of enhancing these critical-thinking-supporting activities. This study aimed to describe the implementation of the Problem-Based Learning (PBL) model and examine the change in students' learning activities that support critical thinking during chemistry instruction. The study employed a Classroom Action Research (CAR) design following the Kemmis and McTaggart model, conducted over three cycles with 36 Grade XI (Phase F) students at SMAN 1 Pancung Soal who were identified through classroom observation and teacher assessment as showing low engagement in these activities. Data were collected using teacher- and student-activity observation sheets validated by expert judges. The results showed a progressive increase in observed learning activities supporting critical thinking, from an average of 39.0% in the pre-cycle stage to 58.0% in Cycle I, 73.6% in Cycle II, and 87.4% in Cycle III (an increase of 48.4 percentage points), placing the students in the highly active category. Improvements were observed across all seven activity indicators, including attention, questioning, expressing opinions, discussion, collaboration, problem-solving enthusiasm, and task punctuality. These findings indicate that PBL implementation was associated with increased learning activities that support critical thinking in chemistry instruction; as this study did not directly measure critical-thinking skills or include a comparison group, whether these activities translate into improved critical-thinking skills should be examined through further research using validated critical-thinking instruments.