With the rapid development of the Internet, increasingly universities and colleges transfer some of their teaching assignments online. Online learning plays an important role in assisting or sometimes substituting for the traditional face-toace learning. An online message board is one of several online communication tools which are used to assist online learning. We have conducted a study on the role of the online message board in teaching one of these courses, an introductory course in calculus-based physics. The study analyzed students? use of the message board and investigated whether use is correlated with performance in the class. Results suggest that students have benefited from using the online message board. Both homework related message board activities and non-learning message boardn activities were found to be correlated significantly to the grades the students earned in the course.