The knowledge domain defines the knowledge of experts. This knowledge consists of declarative and procedural knowledge. Declarative knowledge is a set of facts organised to permit reasoning.
Procedural knowledge relates to how a task is performed.
It consists of arguments and rules to solve problems. There are two ways of modeling the domain model . A number of criterions are stored in a database, and if the student's input data does not meet the criterion, then he is informed of the performance error. Possible solutions are recommended. In the glass box model the knowledge is modeled as an expert system.