Conception of a family of gestures for geometric objects construction and its utilization in an interactive geometry system for mobile devices: GeoTouch

Interactive Geometry (GI) software were developed with the goal of enabling students to explore geometry through the computer, allowing the construction and manipulation of geometric objects, such as, lines, points and circumferences. Traditionally, while using GI systems, the userlearners build a geometric object using the icon associated with it and available in the system interface. Literature indicates that this type of system can facilitate the learning of geometry. Nevertheless, there are studies suggesting that the reduction of icons in the interface can be beneficial for novice users, reducing the difficulty of locating the desired icon among several ones. This difficulty, beyond generating frustration and consequent lack of motivation, can divert the focus of learning, with the learners struggling to learn how to use the system and not to the geometric concepts. In this context, this paper proposes the reduction of icons at GI systems interfaces through the definition of a family of natural gestures that can be used to build and manipulate geometric objects. These gestures are designed to not only reduce the number of visual elements in screen, but also facilitate the learning of geometric concepts. To validate the proposed gestures we developed a GI system using Gestural Interface for mobile devices called GeoTouch. Usability tests were performed with Geotouch as well as the comparison of it with other three GI systems for mobile devices available to date. Results indicate that the GeoTouch interface, which uses the family of proposed actions, is easier to learn, has fewer usability problems and the severity of the problems encountered affect minimally the user.