We present an intelligent pen-based tutoring system for Statics - the sub-discipline of engineering mechanics

concerned with the analysis of mechanical systems in equilibrium under the action of forces. The system

scaffolds students in the construction of free-body diagrams and equilibrium equations for planar devices

comprised of one or more rigid bodies.

While there has been extensive research in intelligent tutoring systems, most existing systems rely

on traditional WIMP (Windows, Icons, Menus, Pointer) interfaces. With these systems, students typically

select the correct problem solution from among a set of predefined choices. With our pen-based interface, by

contrast, students are guided in constructing solutions from scratch, mirroring the way they solve problems

in ordinary practice, which recent research suggests is particularly important for effective instruction.

Our system embodies several innovations including a novel instructional technique that focuses

students' attention on a system boundary as a tool for constructing free body diagrams, a tutorial feedback

system based on "buggy rules" that attempt to diagnose and correct problem-solving errors typical of novice

students, and a hierarchical feedback system which promotes independent problem-solving skills. In winter

2010, the tutoring system was used by 100 students in an undergraduate Statics course at our university.

Results from pre- and posttests reveal measurable learning gains even after only a short exposure to the

system. In an attitudinal survey, students reported that, while there is room for improvement, the interface was preferable to a WIMP interface and the methodology implemented in the system was valuable for

learning Statics.