Gamification--the use of game elements in serious contexts, has been prevalent to enhance users' motivation and engagement in difficult activities. In the literature related to higher education, the use of gamification has emerged as a new pedagogical approach in order to improve students' learning behaviors. On the other hand, traditional education research suggested that working in groups can enhance students' learning behaviors. However, no study has been found in the literature that investigates these two distinct concepts in education domain. Therefore, this research aims to explore the effect of different group sizes and gamification on students' learning behaviors. For this purpose, the study has explored the comparison between gamification and traditional classroom settings on students' learning behavior with different group sizes: individual, small group, and large group settings. Further, the comparison of students' learning behaviors in gamification environment within different group settings over time has also been investigated in this research. The analysis suggests that different group sizes can have varying impacts on students' perception of the course in gamification environment over time. Moreover, it was observed that group size only affects students' interest, comparison, and discouragement in gamification environment, but does not affect their effort, perceived choice, perceived competence, tension, or motivation. Also, it was found that gamification does not affect the perceived competence of students in any of the group settings. These results can be useful in future decisions about the optimal classroom size, group activities, and group sizes in other activities in larger classrooms.