Enhancing Biological Literacy: A Quasi-Experimental Study on the Comparative Effectiveness of Problem-Based Learning and Traditional Lecture Method in Secondary School Biology Education

The persistent pedagogical debate between teacher-centered and student-centered instructional approaches remains highly relevant in science education. While the traditional lecture method (TLM) is efficient for content delivery, its effectiveness in fostering higher-order cognitive skills (HOCS) and deep conceptual understanding is questioned. Problem-Based Learning (PBL) has emerged as a potent alternative, yet robust quantitative evidence of its comparative effectiveness in secondary school biology remains fragmented. This study aimed to rigorously compare the effectiveness of a PBL intervention against a standard TLM approach on academic achievement, conceptual understanding, and critical thinking disposition in a secondary school biology curriculum. A quasi-experimental, non-equivalent control group design was employed. The sample comprised 124 tenth-grade students (mean age 15.6 years) from four intact biology classes in a public secondary school. Two classes (n=62) were randomly assigned to the PBL group, and two (n=62) to the TLM group. The intervention spanned an eight-week instructional unit on "Human Physiology and Homeostasis." Instruments included the Biology Achievement Test (BAT), a two-tier Diagnostic Test for Conceptual Understanding in Homeostasis (DT-CUH), and the California Critical Thinking Disposition Inventory (CCTDI). Data were analyzed using descriptive statistics and Analysis of Covariance (ANCOVA), with pretest scores as the covariate. After controlling for pretest differences, the PBL group demonstrated statistically significantly higher post-test scores on academic achievement (F(1, 121) = 28.41, p < .001, η² = 0.19), conceptual understanding (F(1, 121) = 45.67, p < .001, η² = 0.27), and critical thinking disposition (F(1, 121) = 12.83, p < .001, η² = 0.10) compared to the TLM group. The effect sizes indicated a large impact on conceptual understanding and a medium-to-large impact on achievement and critical thinking. PBL is significantly more effective than TLM in promoting not just rote learning but, more critically, deep conceptual understanding and the disposition for critical thinking in biology. The findings provide strong empirical justification for a paradigm shift in biology pedagogy from passive reception to active, problem-driven inquiry. Implications for curriculum design, teacher professional development, and educational policy are discussed.