This study examined the effect of brain-based learning instructional approach (BBLIA) on
secondary school students’ retention of Newtonian Physics, moderated by gender, in Onitsha
Education Zone, Nigeria. Three research questions and three null hypotheses were tested at
0.05 significance level using a quasi-experimental pretest-posttest delayed posttest design.
The sample comprised 52 SS2 Physics students drawn from a population of 3,618 using
multistage sampling. Physics Retention Test (PRT) was administered as pretest, posttest, and
delayed posttest (three weeks after posttest). Reliability of PRT was 0.84 (KR-20). The
experimental group (n=25) was taught with BBLIA, while the control group (n=27) received
lecture method. Data were analysed using mean, standard deviation, and ANCOVA. Results
showed that BBLIA led to significantly higher retention scores and lower knowledge loss
compared to lecture method. No significant gender difference in retention was found among
BBLIA-taught students, and no significant interaction effect between instructional strategy
and gender on retention was observed, although the interaction was disordinal. It was
concluded that BBLIA promotes durable retention of Newtonian Physics concepts equally for
male and female students. The study recommended the institutional adoption of BBLIA to
ensure equitable long-term learning outcomes.