This study was undertaken to determine the effect of teaching learning skills on achievement level of students in senior secondary physical science. It compared analysis of covariance (ANCOVA) and independent sample t-test on the residualized gain scores, as methods of data analysis in the study. The study further investigated the relationship between age/gender and the achievement level in the subject and explored the extent to which, students use learning skills. Two hundred and twenty form three students from four secondary schools selected from Central Eastern Education Division (CEED) were used. A quasi-experimental design was used and eighty-two girls and one hundred and thirty-eight boys sat for physical science pre and post tests. Further, twenty boys and twenty girls completed a Motivated Strategy for Learning Questionnaire (MSLQ). ANCOVA showed that there were statistically significant differences in the achievement level between the experimental and the control groups at alpha level of 0.05. This implied that the intervention improved the performance of the experimental group. ANCOVA and independent sample t-test on the residualized gain scores yielded similar results except for the effect size (ES) which was lower for the ANCOVA. Partial correlation coefficients between the achievement scores and age showed that the effects of the intervention were age dependent. Younger students gained more from the exposure to the learning skills than their older counterparts. However, point biserial correlations between achievement scores and gender showed weak correlations. Generally, there were no significant differences in the achievement levels based on gender. Chi square test of homogeneity on the responses to the MSLQ showed that there were statistically significant differences between the experimental and the control groups in their use of learning skills. The study concluded that the teaching of the learning skills improved achievement level of students in senior secondary physical science. Generally, ANCOVA and an independent sample t-test produced similar results and could be used when analyzing data in quasi-experimental studies. The effects of the intervention are age dependent while gender has little influence on the achievement level. However, the intervention affects how students use learning skills when learning senior secondary physical science. The details are presented in the study.