There is a growing interest in using e-learning for geometry and / or technical drawing teaching both in distance education and as a supplement to in-class courses. Although there are many geometry drawing programs being used for educational purposes, some shortcomings may be identified in their user interfaces when used as a (partial) replacement for paper and pencil practice.
Most of those programs adopt a conventional Graphic User Interface (GUI), based on windows, icons, menus and pointing (WIMP). Due to this, like any other software, they demand some user’s time to be mastered. Likewise, most of them have many features, allowing a full range of graphical constructions (tangent, parallel and perpendicular lines, middle point, bisectors, inscribed and circumscribed circles etc.) to be executed with a few clicks. Finally, their GUIs are very abstract, far apart from the drawing instruments the students use in classroom.
A non-intuitive GUI is a particular problem in that context because, among other reasons, as it is widely known, the credits assigned to graphics disciplines, with a few exceptions, have been reduced worldwide. Hence, it is very undesirable to have a student spending time to learn how to drive a new program instead of practicing the target topics of a course in the short time available. Furthermore, as this kind of software usually covers only a small part of a discipline contents its use is occasional and is not worth investing much time for learning it.
Different from a CAD system, where drawing efficiency is among the most important requirements, an educational tool must sacrifice execution speed in favor of pedagogic issues, if needed. Therefore, a plethora of features for easy execution of any foreseeable construction is not only undesirable because it precludes the student of performing a geometrical construction the way he must practice, but also makes steeper the software learning curve.
Concerning the abstraction aspect of the GUI, we are not sure to which extent the use of an artificial, computer interface for drawing can hamper the abilities of an apprentice regarding the correct manipulation of drawing instruments (compass, triangles, ruler, pencil). We plan to investigate this issue.
Therefore, we conclude that an educational geometry drawing software GUI should be intuitive and concrete. This paper describes an interface based on a real world metaphor featuring a compass, a 45° triangle, a 30°/60° triangle, a pencil and an eraser. This interface is under development by the authors and will integrate an online dynamic geometry educational software.
The virtual instruments in the proposed interface closely emulate their real counterparts (both visually and behaviorally) and it is hoped that their manipulation will be intuitive enough to dispense any explanation or instruction. Towards this goal, a major issue is the fact that the interaction in the proposed interface is one-handed (select/drag with the mouse) while the user utilizes both hands when interacting with the drawing instruments in the real world. Some clever techniques were employed to circumvent this problem and, at the same time, keep the interaction intuitive.