In this paper, the authors describe the development of a Web bulletin board system and its implementation and evaluation in school mathematics classes. In their dynamic studies of Web-collaborative learning during the past few years, they have found that problems with such computerized systems lie in their inability to show how notes relate to each other through links. To solve this problem, they developed a Web bulletin board system enhanced by a knowledge map. The system is called NakSun. Using NakSun, learners can determine the coordinates, or location, of a node that has been entered. They can also link notes together using the system in real time. NakSun was implemented in mathematics classes in a few junior high schools in Japan on three separate occasions. Their results found that the use of the knowledge map was a comparatively effective tool to facilitate collaborative learning. Furthermore, their results also indicate that it is essential for students to obtain sufficient experience in using the system. An interesting finding was that displaying all notes in a sequential order was also essential for learners, as it enabled them to take a glance at many ideas and views at one time.