The aim of this research is twofold; to investigate the effects of cooperative group-based work activities on children's pattern recognition skills in pre-school and to examine the teachers' opinions about the implementation process. In line with this objective, for the study, 57 children (25 girls and 32 boys) were chosen from two private schools in the Adana city center. A pattern recognition test addressing pattern recognition skills, pre-test, and post-test were used as the data collection tools. Furthermore, semi-structured interviews were conducted at the beginning and end of the implementation to obtain the teachers' perspectives about the implementation process. During the implementation, 2 experimental groups followed a cooperative group work activities program, while a control group was taught individually. The data analysis indicated that the children in the experimental groups showed greater progress in terms of pattern recognition skills than their peers in the control group. The interview findings from teachers indicated that in addition to the pattern recognition skills, the children developed additional skills such as solidarity, sharing, active listening, and fulfilling their personal responsibilities in the group work activities. One of the significant findings of the study was that the teachers changed their negative attitudes toward the use of pre-school cooperative group work activities. Therefore, cooperative group work is recommended for use in pre-schools to reinforce children's pattern recognition skills and to develop important social skills.