Abstract

• The main purpose of the present study is to investigate the effectiveness of cooperative learning strategies on students' achievement in middle school science. It is an experimental research. Treatment is based on instructional design concerning cooperative learning strategies. According to the format of that design, (7) sample lesson plans of learning materials were constructed. The target population is Grade Six students. Two high schools that situated in Mayangone and Insein Townships in Yangon Region were selected by random sampling method. A total of (120) students and (4) science teachers participated in it. To study the effectiveness of cooperative learning strategies on students' achievement in middle school science, one of the true experimental designs, pretest- posttest only control group design was used. Treatments were conducted separately to two groups. The experimental groups were taught according to the cooperative learning strategies. The control groups were taught as formal. Learning materials were selected from Chapter (5), Earth and Space, from Grade Six General Science Textbook. The posttest scores or data were analyzed with independent samples t test to test the hypotheses of this study. The instrument used in this study was a posttest. The result of this study showed that, there was a significant difference in the achievements of science learning between the students who were taught by using cooperative learning strategies and those who were not. It can be suggested that the cooperative learning strategies should be used in the classroom in teaching middle school science. Therefore, it was concluded that cooperative learning strategies brings positive contributions to the middle school science.