An apparatus and a system to teach a user a subject based on his questions. The system allows the user to control his learning process, and helps to fill in gaps of misunderstanding in the subject. In one embodiment, the system, including a database, presents study materials on the subject to the user....http://www.google.de/patents/US6336029?utm_source=gb-gplus-sharePatent US6336029 - Method and system for providing information in response to questions
