This paper gives an overview of our tutoring system, B2. It describes the natural language and knowledge representation components of B2, and our approach to the representation of questions and requests. The domain that we have developed most thoroughly helps medical students learn a statistical model for medical diagnosis. Many of the examples will be taken from this domain. According to B2’s plans for tutoring, the system does this by generating story problems that describe a scenario and then asking the student about conclusions that might be drawn. B2 also supports requests to explain its reasoning and questions about facts.