During the last decade, the interest in distance learning tools has grown thanks to the availability of bandwidth and powerful computers. Thus, distance learning has moved from a particular environments (such as industry), to a larger community. The main challenge of last generation e-learning tools is to provide courses tailored to the different student backgrounds; this pushes research to create an adaptive environment able to just-in-time craft the best path for each student. The paper deals with this problem, also presenting a Web based prototype of an e-learning tool to provide users with all paths, moving from knowledge of a student to desired knowledge.