Teachers' motivational strategies can be categorised into two types of motivating styles--autonomy-supportive style versus controlling style (Reeve in Educ Psychol 44:159-175, 2009). Several factors can affect the teachers' use of motivational strategies, and student-related factors are some influential reasons. In this study, we focussed on identifying the student-related reasons that could affect the teachers' motivating styles through 56 teacher interviews from 17 secondary schools across Singapore. From the teachers' accounts, we identified "student profiles", "students' behaviours", "students' engagements", and "students' feedback" as the student-related factors that could affect the teachers' motivating styles. By identifying these factors, we hope to raise awareness amongst the teachers (at the personal level) and their social environments (at the contextual level) on what can facilitate or thwart the expression of autonomy-supportive teaching. We also hope to provide useful information on what the social environments can do to support teachers in autonomy-supportive teaching.