Abstract

• The main purpose of this study was to investigate the effectiveness of cooperative learning in teaching mathematics at the middle school level. Quantitative study was used to compare the mathematics achievement of students who received instruction with cooperative learning with those who did not receive. The design adopted for quantitative study was one of the quasiexperimental designs, nonequivalent control group design. The sample schools, Kyitaung Kan, Pobathiri and No. (21), BEHS, Pobathiri were selected from Nay Pyi Taw by simple random sampling method. The subjects were (118) Grade Nine students from Kyitaung Kan and (71) from No. (21), BEHS. The students from each school were divided into two groups: control and experimental. The instruments used in this study were pretest and posttest. Learning materials were selected from Grade Nine mathematics textbook: chapters (10) from mathematics textbook volume I and chapter (3) from mathematics textbook volume II. By using independent samples ttest, there were significantly differences between students who received instruction with cooperative learning and those who did not receive it on the scores of mathematics achievement for Kyitaung Kan, Pobathiri (t = 3.330, **p<.01) and No. (21) BEHS, Pobathiri (t = 2.992, **p<.01). It can be interpreted that teaching by cooperative learning methods had a significant effect on cognitive levels of mathematics instruction. Thus, this study made a positive contribution to the development of mathematics education in Myanmar.