the effects of homogeneous small groups on the efficacy of problem-based learning

introduction: problem-based learning (pbl) as a learning style has gained a special position amongst different levels of education systems, and many different approaches, such as tutor education, proper scenario presentation, etc., are used to increase its efficiency. however, the role of homogeneous groups to facilitate team working has never been studied. the purpose of this study is to examine the effect of selective group allocation in pbl efficiency. methods: in this semi-experimental double-blinded study, 40 students of medicine during their externship in the radiology department were divided into two equivalent groups based on their grade average points. the same topics and the same instructors were chosen for both groups. in the control group, the students were randomly divided into four subgroups each with five members.  the subgroups in the study group, on the other hand, were homogenized based on their grade average points. results: the students’ rate of learning of the theoretical topics and their performance in reporting and interpreting the stereotypes in radiology were measured at the beginning and at the end of the study in both groups by two questionnaires with alpha krunback of 0.87 and 0.85. all students were male with the mean age of 23.7 years ± 1.19. age, grade point average of the students in the last semester and the mean of their pre and post-test scores in both groups showed a normal pattern of distribution (p>0.05).  the learning and performance scores in each group at the beginning and at the end of the course showed a statistically significant difference with a p value of 0.011 and 0.03, respectively. conclusion: homogenizing the pbl groups with allocation of more competent student in each group plays a complementary tutor role and boosts the level of learning by enhancing group dynamicity. keyworsds:homogenization, problem-based learning, competent students