This study is aimed at finding the effects of Mastery Learning Approach (MLA) on students’ Achievement in Integrated Science. The study was Quasi-experimental Non-randomized Pretest-Posttest Control Group Design. The target population comprised of Junior Secondary School Students (JSS) in Delta Central Senatorial District of Delta State, Nigeria. The accessible population was JSS III Students drawn from the district co-educational schools in the Senatorial District. Purposive sampling technique was used to obtain a sample of four co-educational secondary schools. Each school provided one JS III class for the study, hence a total of 120 students were involved. The students were taught the same Integrated Science topic of Drug Abuse and Metabolism in the Human body. In the experimental group MLA teaching method was used while the conventional method was used in the control group. The experimental group was exposed to MLA for a period of four weeks. The researcher trained the teachers in the experimental group on the technique of MLA before the treatment. Pretest was administered before treatment and a posttest after four weeks of treatment. The instrument used in the study was Integrated Science Achievement Test (ISAT) to measure students’ achievement. The instrument was pilot tested to ascertain the reliability. The reliability co-efficient alpha was 0.74. Data was analyzed using ANCOVA statistics. Hypothesis was accepted or rejected at 0.05 significant level. The result of the study show that MLA teaching method resulted in higher achievement. The researcher concluded that MLA is an effective teaching method, which Integrated Science teachers should be encouraged to use and should be implemented in all teachers’ education programmes in Nigeria and other African nations
Keywords: Conventional Teaching Method, Experimental and Control Groups, Integrated Science Achievement, Junior Secondary School Students, Mastery Learning Approach
