With the advances in Internet technologies, online education is fast gaining ground as an extension to traditional education. Webcast allows lectures conducted on campus to be viewed by students located at remote sites by streaming the audio and video content over Internet Protocol (IP) networks. However when used alone, webcast does not provide the form of user-to-user interaction that is so important in education. This article presents a collaboration system that can be used to facilitate interaction among users in a live webcast environment. The collaboration system supports real-time communication in both text and audio modes. To allow discussions to be carried out in an orderly manner, a virtual hand-raising scheme is implemented to put more control in the hands of the instructor. Using a topic browser, students can access content of previous discussions and use them as reference sources for any new question they may wish to raise. To allow offline viewing, the discussion content are automatically saved to the local computer at the end of each collaboration session.