Student-designed games (SDG) are a student-centred approach that motivates students to work together while designing and playing their own games based on their ability level. The purpose of this study was to investigate students' social interactions during 11 lessons of SDG focused on target games. Participants were 27 fifth-graders. Lessons were based on Hastie (2010) ["Student-designed games." Champaign, IL: Human Kinetics]. Five-Step SDG implementation process. Field notes and post-intervention interviews transcriptions were analysed through a systematic process of inductive analysis. Two themes were generated based on field note observations and students' focus interviews: (a) who is the leader and (b) leadership dispute. The results showed that within coeducational groups, girls took the leadership roles. It was found that during intra-group interactions, leaders who took a more democratic approach motivated students engagement, and promoted opportunities for compromising during decision-making process.