Course materials may contain a variety of media, including text, graphic, audio and video. Any student with internet access can view these materials. Teachers and students can communicate with each other via email or through discussion forums. Dr. Zaslavsky's GIS course and Dr. Whitney's CS courses are good examples of asynchronous distance learning. Web-based synchronous distance learning can achieve a greater degree of information sharing between students and teachers.
Participants are basically in a virtual classroom via web.
They can listen and see each other. They can share information in text or graphical form. What is more interesting is that they can even share a computer application synchronously. To implement synchronous distance learning, we need a computer program, which is called collaborative environment. This program should be installed on every machine in which teachers or students use.