OBJECTIVE: This study investigates how different team grouping methods and task assignments affect group dynamics, specifically focusing on the presence of free riders and active learners (those who fully engage and contribute to the group). METHODS: This study was conducted in 2020 within a Problem-Based Learning program focused on physical chemistry and pharmaceutics. A total of 255 second-year students were divided into three groups based on their career prospects, their grades, or randomly: (1) Motivation group, (2) Grade group, and (3) Randomized group. Data was collected through post-program questionnaires that included demographic questions, learning behaviors, and peer evaluations. Statistical analyses, including chi-square tests and analysis of variance, were employed to compare group dynamics and learner characteristics. Qualitative comments on team performance were analyzed through coding and categorizing. RESULTS: The Grade group had the highest number of free riders, while the Motivation group had the most active learners. Free riders demonstrated lower grades and self-evaluations, while active learners exhibited higher grades and leadership roles. Motivation based grouping, aligning team tasks with students' career prospects, was associated with higher engagement and fewer free riders. Grouping students based on career prospects promotes active learning, while grouping by academic performance may increase free riding. CONCLUSION: The grouping method that combined students with various Grades may not yield positive effect, and the grouping method based on career prospects have the potential to increase student motivation.