Effect of Problem-Based Learning on Students’ Critical Thinking and Performance in Biology in Imo State

This study examines the effect of problem-based learning on students' critical thinking skills and academic performance in Biology in public secondary schools in Imo State, South East Nigeria. Biology education at the secondary level is central to preparing students for health science and agricultural pathways, yet prevailing lecture-dominated pedagogies are widely criticised for failing to develop analytical reasoning. The study employs a quasi-experimental pretest-posttest control group design, selecting 260 Senior Secondary School Two Biology students from eight schools in Owerri Municipal, Orsu, and Ideato North local government areas. The experimental group received problem-based learning instruction through authentic biological problem scenarios over nine weeks, while the control group received conventional teaching. The Revised Watson-Glaser Critical Thinking Appraisal and a Researcher-Developed Biology Achievement Test served as outcome measures. Hmelo-Silver's Problem-Based Learning Theory and Bloom's Revised Taxonomy inform the framework. MANCOVA was applied to simultaneously assess effects on critical thinking and achievement. Findings are expected to demonstrate significantly higher critical thinking and performance scores in the PBL group compared to controls. Teacher training adequacy for PBL facilitation is examined as an implementation factor. Recommendations address the Imo State Ministry of Education and teacher education institutions on incorporating problem-based learning methodology into Biology teacher preparation programmes and providing structured case scenario libraries for classroom use. Keywords: problem-based learning, critical thinking, Biology achievement, Imo State, secondary education