In formative pilot studies medical students interacting with a simulation-based learning environment were found to require additional support . In particular , students wanted both the interactive qualities of the human tutor's feedback and , access to more expository reference material . To improve the support provided , an explanation-generating component was added to the simulation . This employed rhetorical schemata capable of dynamic specialization to meet multiple communicative goals within a single response . Moreover , responses contained Hyper-media links to pre-stored reference material , allowing the student to follow-up generated explanations with self-directed browsing . The mechanisms for producing help explanation , through rhetorical predicates , are described . An underlying knowledgebase formalism was adopted which permitted the expression of domain concepts in cohered text form , and enabled the generation of textual descriptions of animatedgraph simulation output . Using this prototype as a platform , current work is aimed at supporting knowledge negotiation between computer-based system and student , in order to further the development of students' diagnostic reasoning skills .