Despite the growing number of sketch recognition systems for education, little attention has been paid to how students actually draw in practice. We examine freely-drawn digital logic-diagrams created by students in an electrical engineering class in order to inform the design of a sketch recognition digital circuit simulation tool. Our analysis reveals considerable drawing style variation between students and that standard drawing style restrictions made by sketch recognition systems to aid recognition generally do not match the way students draw. We identify drawing behaviors that can aid recognition while placing fewer unnatural constraints on students' drawing styles, and we describe specific recognition tasks whose solutions will lead to more robust free-sketch recognition systems.

[1] Properties of Real World Digital Logic Diagrams. Alvarado, Christine and Lazzareschi, Michael. Proceedings of 1st International Workshop on Pen-based Learning Technologies. 2007. <pdf>