Compared with face-to-face teaching, online classes are more convenient. However, during online classes, it is more difficult for teachers to observe all students' reactions at the same time. Our system is designed to help teachers to adjust the speed of their lessons by detecting students' head poses. Therefore, it is necessary to capture the head poses of students through their cameras during the class, and estimate their head poses based on their face landmarks. Students show their understanding of the lesson through their head poses. This paper discusses how to estimate students' head poses and, based on that, evaluate students' listening situations.