The rapid growth of the Internet and Instant Messaging (IM) offers new opportunities as well as challenges to both educators and students. In this paper, we propose an Intelligent Tutoring Agent (ITA) that uses the ontology, INFOMAP, and question answering techniques through the Instant Messaging platform for the "operating system" course. The ITA embeds the above techniques in the teaching process and plays the role of a tutoring agent to help a teacher track, record, and understand a student 's status. The ITA interface can interpret natural language to facilitate communication between the student and the tutor. Student can query and learn the concept of "operating system" through MSN Messenger, which ITA adopts as the communication protocol. The proposed ITA is accessible by adding the contact ID: email@example.com to the MSN Messenger contacts list.