The purpose of this study is to investigate the influence on learning and teaching in a Primary 4 English class and how the teacher-researcher reflects on her own teaching while implementing cooperative learning. It is hoped that the findings from this study can provide some useful references for those teachers interested in applying cooperative learning in their classrooms. This study is based on an individual action research.Classroom observations, fieldwork, recordings, questionnaires, and student interviews have been used for data collection. With synthesis and analysis on the data as well as the observation from the teaching and learning process, the teacher-researcher has come to these findings and conclusions. (1) Cooperative (CL) makes students become more interested in English lessons. (2) The results show that there are improvements in students’ English learning attitudes and students’ achievements after the implementation of CL. (3) CL can provide students more opportunities to share ideas with their peers, as it helps to boost their interpersonal relationship. (4) CL can build up students' confidence in expressing their ideas. Keywords: cooperative learning, Primary 4 English teaching, teaching and learning effectiveness, improvements in learners' attitudes