Abstract
This study investigated the effects of Inquiry-Based Learning (IBL) on junior high school students’ conceptual understanding and retention of cell theory in Ghana. A Solomon four-group design was employed to control for possible pretest sensitization effects and to ensure the validity of the findings. Four intact classes from two public junior high schools participated in the study, yielding a total sample of 141 students. The experimental groups were taught using inquiry-based learning strategies that actively engaged students in questioning, investigating, and constructing knowledge, whereas the control groups received conventional teacher-centered instruction. Data were collected using a Cell Theory Concept Test (CTCT) administered as a pretest, posttest, and retention test. Two-way analysis of variance (ANOVA) results revealed a statistically significant main effect of instructional strategy on students’ conceptual understanding of cell theory, favoring those exposed to inquiry-based learning. There were no significant pretest or interaction effects, indicating that the observed differences were attributable to the instructional intervention rather than testing effects. Furthermore, paired-samples t-test results showed that students in the inquiry-based groups demonstrated improved or sustained retention of cell theory concepts three weeks after instruction. These findings provide strong empirical evidence that inquiry-based learning enhances both immediate conceptual understanding and longer-term retention of biological concepts. The study recommends integrating inquiry-based instructional strategies into junior high school biology classrooms in Ghana to promote meaningful learning and improve students’ academic outcomes.