motivation is essential for the students’ involvement at school. for the self-determination theory, the teacher’s motivational style, either controller or promoter of autonomy, contributes to foster the occurrence of qualitatively differentiated types of motivation. in this study of exploratory nature the interactions among two teachers and their students were observed. the sample was composed according to the score of 39 teachers in the motivational style assessment, by means of the application of a self-report instrument, named problems at school. out of this total, two teachers, one with an autonomy promoting motivational style and the other one, a control-oriented one, had their classes observed along seven sessions, with the aim of collecting data for the elaboration of a protocol containing interaction categories. seven other observation sessions were then carried out. the results have indicated that, despite findings of differences between the motivational style assessment performances, the teachers preferably interacted with their students in a controlling manner. however, the autonomy promoter teacher interacted less controllably than the controlling teacher, as regards the management of time reserved for the accomplishment of class activities, as well as offering informative feedback. the educational implications of the results are also discussed.