Experimentally based, longitudinally designed, teacher-focused intervention to help physical education teachers be more autonomy supportive toward their students.

Using the field’s state-of-the-art knowledge, we designed, implemented, and assessed the effectiveness of an intervention to help physical education (PE) teachers be more autonomy supportive during instruction. Nineteen secondary-school PE teachers in Seoul were randomly assigned into either an experimental or a delayed-treatment control group, and their 1,158 students self-reported their course-related psychological need satisfaction, autonomous motivation, amotivation, classroom engagement, skill development, future intentions, and academic achievement at the beginning, middle, and end of the semester. Observers’ ratings and students’ self-reports confirmed that the intervention was successful. Repeated-measures ANCOVAs showed that the students of teachers in the experimental group showed midsemester and end-of-semester improvements in all dependent measures. A multilevel structural equation model mediation analysis showed why the teacher-training program produced improvements in all six student outcome...