This paper presents a characterization of computer-based interactions by which learners can explore and investigate visual mathematical representations (VMRs). VMRs (e.g., geometric structures, graphs, and diagrams) refer to graphical representations that visually encode properties and relationships of mathematical structures and concepts. Currently, most mathematical tools provide methods by which a learner can interact with these representations. Interaction, in such cases, mediates between the VMR and the thinking, reasoning, and intentions of the learner, and is often intended to support the cognitive tasks that the learner may want to perform on or with the representation. This paper brings together a diverse set of interaction techniques and categorizes and describes them according to their common characteristics, goals, intended benefits, and features. In this way, this paper aims to provide a preliminary framework to help designers of mathematical cognitive tools in their selection and analysis of different interaction techniques as well as to foster the design of more innovative interactive mathematical tools. An effort is made to demonstrate how the different interaction techniques developed in the context of other disciplines (e.g., information visualization) can support a diverse set of mathematical tasks and activities involving VMRs. NOTES 1 In this paper, the terms learner, user, problem solver, explorer, and investigator convey the same meaning. 2 These tools, also called cognitive technologies or mindtools, are intended to support human cognitive processes and thinking. Examples of these tools include interactive visualization software to explore patterns in a body of information, mind mapping tools to help externalize and organize thoughts and concepts, and online interactive mathematical applets to investigate how velocity and position graphs relate. 3 The nodes of this diagram represent Ks having different orientations, and its links represent how these Ks can be connected. KAMRAN SEDIG AND MARK SUMNER 48 4 The 8-puzzle is a game consisting of a 3 Â 3 square grid. Eight of the squares have numbers from 1 to 8, and one of the squares is empty. This allows for moving the other 8 squares around into different positions until the squares are arranged in an ascending order, with the last square empty.
VISUAL MATHEMATICAL REPRESENTATIONS