Teaching with a classroom feedback system can benefit both teaching and learning practices of interactivity. In this paper, we propose a dual-channel classroom feedback system integrated with a back-end e-Learning system. The system consists of learning agents running on the students' computers and a teaching agent running on the instructor's computer. The learning agent collects both instructional and social responses from the students and then sends them back to the instructor's computer through a two-channel mechanism. The instructional responses are obtained by recognizing the spoken keywords; while the social responses are obtained by analyzing the social signals provided by students' head movements. Later, the teaching agent displays the summarized responses on the teaching dashboard for the instructor to evaluate their teaching practices. Empirical experiment results show that the system has an acceptable performance and provides enhanced interactivity in both learning and teaching. Also, further analysis reveals that the dual-channel mechanism not only provides the basic functions of a classroom feedback system, the student's responses to the instructor's questions, but also promotes both students and instructors to be engaged and attentive in class. As the two-channel feedback mechanism can be embedded into an e-Learning system, the proposed system is an enhancement of a digital classroom environment. In short, with the help of the two-channel feedback mechanism, interactivity on teaching practices and learning activities can be greatly improved. Students can then acquire a much better learning experience and satisfaction.