In recent years, researchers have attempted to develop more effective distance education systems. Nevertheless, students in network-based learning environments may need additional guidance and assistance when they encounter problems in learning certain concepts. Therefore, it is important to provide learning guidance in a distance learning environment. In this paper, we propose a data mining approach that is capable of assisting teachers to provide information needed for guiding students during the learning process. Several experiments on science courses have shown the effectiveness of applying the novel approach.