The Effect of Discovery Learning Model on Students’ Critical Thinking Skills in Biology Learning at SMAN 1 Dampelas

Critical thinking skills are essential in biology learning; however, many classroom practices remain teacher-centered, limiting students’ opportunities to engage in higher-order thinking processes. Although previous studies have reported the potential of Discovery Learning to enhance critical thinking, evidence regarding its effectiveness in secondary biology education remains limited, particularly in the context of Indonesian high schools. Therefore, this study aimed to examine the effect of the Discovery Learning model on students’ critical thinking skills in biology learning at SMAN 1 Dampelas. A quasi-experimental study employing a nonequivalent control group design was conducted with 48 Grade XI science students, consisting of 24 students in the experimental class and 24 students in the control class. Data were collected using validated pretest and posttest instruments based on Facione’s critical thinking framework and analyzed using normalized gain (N-Gain), the Shapiro–Wilk normality test, Levene’s homogeneity test, and an independent-samples t-test. The results showed that the experimental class achieved a higher mean N-Gain score (0.71; high category) than the control class (0.58; moderate category). Furthermore, the independent-samples t-test revealed a statistically significant difference between the two groups (t = 3.678, p = 0.001), indicating that Discovery Learning was more effective than conventional instruction in improving students’ critical thinking skills. These findings support constructivist learning theory by demonstrating that Discovery Learning promotes active knowledge construction through inquiry and problem-solving activities. Practically, the study highlights the importance of implementing student-centered learning environments to foster critical thinking skills in biology education.