A pen-centric tutoring system which teaches arithmetics of fractional expression is designed and implemented. The system, named PAT (Pen-based Arithmetic Tutor), utilizes pen as the input device to provide an easy-to-use natural interface to the student. PAT monitors the student's actions step by step to understand how the student solves the problem and what he/she does not understand. Based on the system's understanding on the student's understanding, it generates the most suitable exercise for the student and gives advices if necessary.
The system consists of four major components. Those are user interface, problem solving, student modelling, and tutoring strategy modules. The user interface module recognizes hand-written expressions and converts them to textual form. A real-time trainer is provided by which the student can teach his/her own writing style to the system. The problem solving module detects differences between previous and current expressions each of which is represented as a tree structure. The student modelling module constructs a student model which represents the student's knowledge state by attaching a degree of mastering on each of hierarchically organized concepts to learn. The degree of mastering, which is based on the student's intentions and misconceptions, is computed by applying predefined rules on the difference detected by the problem solving module. When the student skips several intermediate computational steps, the omitted steps are guessed by comparing with an ideal solution. The tutoring strategy module selects the most suitable exercise based on the student model and generates helpful messages when appropriate.
As expected, the system provides a very easy interface and it has been demonstrated that such a pen-centric mode of interaction is effective for teaching arithmetics to elementary school children.
