Abstract

This study investigated the comparative effects of inquiry, problem-solving and lecture methods on the academic achievement and retention of Physics students in Delta North Senatorial District, Delta State, Nigeria. The study also examined the moderating effect of sex. Two research questions and two corresponding null hypotheses guided the study, tested at the 0.05 level of significance. A pretest, posttest, delayed posttest, quasi-experimental planned variation design was adopted. The population comprised 16,473 Senior Secondary II Physics students in Delta North Senatorial District, from which a sample of 345 students was drawn from six public co-educational secondary schools using simple random sampling. Data were collected using a 50-item Physics Achievement Test (PAT) developed from past West African Examinations Council (WAEC) questions, validated by three experts, and possessing a reliability coefficient of 0.72 (Kuder-Richardson Formula 21). Data were analysed using mean, standard deviation, t-test, Analysis of Variance (ANOVA). Results showed that students taught with inquiry teaching strategy recorded the highest achievement gain (31.39 points) and retention rate (94%), followed by problem-solving strategy (28.26 points; 93% retention), while the lecture method recorded the lowest achievement gain (5.26 points) and retention rate (87%). No significant difference was found between male and female students' achievement or retention scores. The study concluded that inquiry and problem-solving strategies are more effective than the lecture method in enhancing achievement and retention in Physics, regardless of students' sex, and recommended their wider adoption in secondary school Physics instruction.