The forms of organization supporting social interaction are favored in the pedagogical and didactical models of work of educational institutions of progressive orientation. Interaction between students during work in small groups is viewed as a significant factor in enabling them for a quality decision-making in the process of interactive work. The paper investigates whether, from teachers' perspective, the age of students is a significant predictor of the quality of decision-making during work in small groups. The attitudes of 162 teachers towards the quality of decisions that students make while working in small groups were examined by using the KDO-MG scale. The assumption that there is a tendency for the quality of decision-making to increase with the progression of students' age was verified by using a single linear regression analysis. The results confirmed that, according to teachers, the age of students can be considered a predictor of the quality of decision-making during work in small groups. It is a relatively weak, but stable prediction. Teachers do not question the positive effect of students' work in small groups, but they believe that it is slightly determined by their age, so that the older the students are, the higher the quality of decision-making during work in small groups.