Virtual-patient simulators play an important role in modern medical education. These simulators provide a safe environment for learning, give contextual feedback to learners, and allow the learner to move beyond the time and space constraints of traditional face-to-face medical instruction. In this paper, we present an interactive simulation system, LiveBook. This system interacts with students in natural language, and provides detailed feedback on the student's performance after a case has been studied. The first LiveBook cases are currently being piloted in the area of Pediatrics, but the system is applicable to all areas of medicine.