We proposed to study self-regulated learning (SRL) of 11th grade students in a PBL classroom (n = 36). The data were collected in November 2016 using Students' Self-Regulation Strategy Inventory (Students' SRSI), Teachers' Self-Regulation Strategy Inventory (Teachers' SRSI), students' interviews forms, students' reflections, and the teachers' notes. Descriptive statistics (percentages, means, and standard deviations) and descriptive analysis were used to analyse the data. We found that in the PBL classroom, the students demonstrated self-regulated learning in three phases -- the forethought phase, the performance phase, and the self-reflection phase -- at high levels.