Abstract
This study concerns teacher–student transactions regarding undisciplined actions in physical education. Two lessons (A and B) of the same teacher were observed and recorded. The speech acts of teacher and students were transcribed verbatim and analysed from individual transactions. The observational data were triangulated with the data from post-lesson interviews. The results showed that during transactions in which the teacher prescribed the students to act, they did not produce undisciplined actions but performed the prescribed actions only in his presence and that, during the same transactions based on the teacher’s prescriptive actions, the number of students’ undisciplined actions decreased in Lesson A and increased in Lesson B. When students produced undisciplined actions at the beginning of Lesson A, prescriptive actions were efficient; when students did not performed undisciplined actions at the beginning of Lesson B, prescriptive actions provoked the appearance of these undisciplined actions.