The purpose of this study was to test the best mix of reciprocal peer tutoring with direct teaching methods to improve students' achievement in secondary school physics teaching in content-focused and high-stake examination-oriented curriculum. Data was gathered from three equivalent grade-9 sections and assigned to three different intervention groups in pre-test post-test multi-level quasi-experimental design. The three groups used reciprocal peer tutoring once a week (N=46), twice a week (N=46) and three lessons in a week (N=51) for 9 weeks in two physics units. Results were that reciprocal peer tutoring helped in improving physics achievement of secondary school students (R2=0.316) in favour of low achieving (P=0.001) and female students (P=0.038) when it is used as a unilateral pedagogy. The conclusion is that reciprocal peer tutoring used as a unitary classroom pedagogy helped all students and differentially less able and female secondary school students to enhance their physics achievement to some extent without negatively impacting their learning. Further replication research with a comparison group was recommended to find a conclusive evidence if the observed failure of mixing pedagogy persists.