A Dictionary of Gestures for Multitouch-based Interactive Geometry Software Isabela Gasparini1, Riichiro Mizoguchi2
Helena M. Reis, Seiji Isotani University of São Paulo São Carlos, Brazil
[email protected],
[email protected]
Abstract— Interactive Geometry software (IGS) are tools that help students to explore geometry concepts using computers. Most of IGS interfaces developed to date are heavily based on the desktop model of user interaction where the user input comes from the selection of icons and drop-down menus with the help of a mouse and a keyboard. Nevertheless, with the widespread adoption of smartphones, tablets and other devices with multitouch screens the tradition interfaces of IGS became inadequate. Thus, this study presents the development of a dictionary of gestures for interacting with IGS. It completely removes the need of icons and drop-down menus to create and manipulate geometric objects. To evaluate these gestures we implement them in an IGS for mobile device called Geotouch. Then, we conducted a usability study with five experts to compare Geotouch with other three IGS currently available. The results indicate that Geotouch has less usability problems and enable to build geometric objects faster and with fewer errors. Keywords-gestural interfaces, interactive geometry, dictionary of gestures, mobile devices
I. INTRODUCTION Interactive Geometry Software (GI) enables students to construct and manipulate geometric objects (such as points, lines and circumferences) with the use of technology [6]. In terms of user interaction, the interfaces of this software are important to reduce students’ mistakes and frustration while building geometric figures [8]. Therefore, to develop a GI software, it is important that both pedagogical and design aspects are taken into consideration [1], as they may contribute to maximize learning effectiveness and reduce the cognitive load required to deal with the GI interface [7]. [5] and [7] carried out an interface analysis to correlate cognitive load and the number of icons displayed on the graphical user interface (GUI). The results suggested that interfaces that present more icons can be beneficial for experienced users, but can overwhelm novice users. This happens due to the difficulty of memorizing the location and figure of the desired icon. If the figures that represents these icons are similar, more errors are reported. Consequently, demotivation and frustration of students increases during the process of learning. The use of gestural interfaces can contribute to the reduction of elements in an interface, making it visually simpler [2]. Thus, the main objective of this paper is to present the development of a dictionary gestures for GI software for mobile devices. The rest of this paper is organized as follows: in Section 2, the related work is presented. Section 3 briefly details definition of gestures.
2
1 State University of Santa Catarina Japan Advanced Institute of Science and Technology
[email protected],
[email protected]
Section 4 provides a discussion proof of concepts and the methodology used. Section 5 presents, threats to validity and finally, in Section 6, we present our concluding remarks. II.
RELATED WORK
According to [4] there are few studies that demonstrate the use of interaction through gestures in GI software. Currently, four GI software use touch-based interactions, namely: Sketchometry, Geogeobra, GeometryPad, GeoTouch. Sketchometry was released in July 2012 and developed at the University of Bayreuth, Germany. The software was implemented in HTML5 (HTML, JavaScript, CSS, SVG, Canvas), which enables it to run in any browser that supports this technology. Geogebra is a well know IG software for desktop device started by Markus Hohenwarter in 2001 and its version for mobile devices was released in 2013. The GeometryPad software was developed by Byte Arithmetic LLC and is available only for mobile devices since 2014. And Finally, GeoTouch [10] developed for Android devices and released in 2013. III.
DEFINITION OF THE GESTURES OF CONSTRUCTION
Some findings in the literature indicate learning benefits when using geometric concepts to draw figures [9]. To explore this benefit, we investigated different gestures and tried to relate them to the geometric properties of an object to be drawn by the student. For example, by using two points, you can draw a straight line; thus, the student should construct two points with a certain distance between them and then draw the line through these two points. We have produced several gesture to build geometric objects. To identify which ones could be both user friendly and beneficial for learning, interviews were conducted with four specialists in the field of mathematics education. The interviews showed that the learning of geometrical concepts can be hindered if the created gestures have no relationship with the geometric properties of the objects. For example, if a circle is drawn with the gesture of a circle, the student will not understand that the circle has a radius x or that all the points of this circle are equidistant from the center, generating conceptual problems that may affect learning. As a result of these interviews, we designed a dictionary of gestures to construct geometric objects as shown in Figure 1. All gestures were created taking into consideration the geometric concepts of the objects. The complete dictionary of gestures with detailed descriptions of each
gesture and their relationships with geometric concepts is available in the following address http://goo.gl/nvAR3Z. The dictionary of gestures consists of a textual description of the object, its relationship with the geometric concepts (if any) and a set of illustrative figures that show how to perform gestures on a multi-touch screen-based interface. These gestures are organized into three categories:
Core Gestures: main gestures of the software that are the basis for the gestures of other categories; Navigation Gestures: gestures for navigation in the software; Basic Gestures: gestures for building geometric objects
Figure 1. Dictionary of Gestures
IV.
PROOF OF CONCEPTS
A GI software, called Geotouch [10], was extended using the dictionary gestures defined in Figure 1. The proof of concepts has the aim of finding usability problems. [2] defines the usability criteria as a set of factors that qualify and quantify how well a person can interact with an interactive software. Geotouch was analyzed together with three GI software available on mobile devices presented in Section 2: (a) GeometryPad, (b) GeoGebra and (c) Sketchometry. We use the usability heuristic defined by Nielsen [2] to evaluate each GI software. The heuristic evaluation proposes a set of criteria in order to find usability problems, which helps experts to evaluate and describe characteristics of interfaces [1, 15]. To perform the heuristic evaluation of the four software, we used a 7-inch tablet with Android operating system and prepared a guide with several activities to build geometric objects. Then, we asked five experts to perform the activities in the guide. After each activity the experts had to analyze each software by using ten criteria: (H01) system status visibility; (H02) Correspondence between the system and the real world; (H03) User control and freedom; (H04) Consistency and standards; (H05) Error prevention; (H06) Recognition rather than memory; (H07) Flexibility and efficiency of use; (H08) Aesthetic and minimalist design; (H09) user to help identify, diagnose and correct errors; (H10) Help and Documentation. A computer was used, so that the experts could highlight usability problems according to each criteria and describe the severity of each problem.
The experts tested for at least two hours each software, completing a total of more than 40 hours of testing. Figure 2 shows the frequency of problems by criteria. It is possible to note that no software had problems related to consistency and standards (H04). This shows a certain maturity of the four software analyzed since they are all adapted versions of interactive geometry software developed for desktop computers.
Figure 2. Frequency of problems found by heuristic and software.
However, a considerable number of problems in heuristic H05 were identified in the four software. That is, no one has features which assist users in preventing errors during the creation of a geometric construction. This problem (error prevention - H05) covers the presentation of icons outside of the standard (i.e. icons commonly used), lack of feature descriptions and error messages or of step by step guides to carry out the activities. That is, the interface design and its components do not prevent users from making mistakes when using building geometric objects. In Figure 3 it is possible to identify the problems encountered in each heuristic and its degree of severity in
the four software. About Geogebra, you can see that the H02 (correspondence between the system and the real world) has greater severity (corresponds to approximately 75% of severity in H02 heuristic), compared to the other problems. This indicates that this problem is critical and needs to be analyzed in future software releases. Problems classified in heuristics H05 (error prevention) and H06 (recognition instead of memory) are related to the second highest level of severity (approximately 50%), while no problems were found relating to H03 heuristics (user control and freedom) and H04 (consistency and standards).
These results indicate that our dictionary of gestures defined in section III and implemented in GeoTouch is more user friendly, reducing the quantity and severity of usability problems identified in the others GI software. V.
CONCLUSION
This paper proposed a dictionary of gestures to build geometric objects in GI software for mobile devices with multi-touch screens. To propose each gesture several gestures were proposed and evaluated by mathematics educators. Then, we carried out a proof of concepts by implementing the proposed gestures in a GI software called GeoTouch and conducing a usability test with five experts. The results suggest that our gestures reduce both the quantity of errors and their severity. In Future work we intend to conduct controlled experiments to verify the impact the proposed dictionary of gestures on students’ learning and performance to build geometric constructions. ACKNOLEDGEMENT The authors thank CNPq, CAPES and FAPESP for their financial support. REFERENCES [1]
[2] [3] Figure 3. Degrees of severity between the heuristics.
In Geometry Pad, we observe that the heuristic related to help to identify, diagnose and correct errors (H09) has problems with greater severity, with approximately 75% of severity and, therefore, a patch to fix it is urgent. The heuristics related to user control and freedom (H03), prevention of errors (H05), recognition instead of memory (H06) and flexibility and use efficiency (H07) had approximately 50% of severity. In Sketchometry, the heuristic related to system status visibility (H01) and help and documentation (H10) showed a high degree of severity, corresponding to approximately 75%. And heuristics related to correspondence between the system and the real world (H02), prevention of errors (H05), recognition instead of memory (H06), flexibility and efficiency of use (H07) and help to identify, diagnose and correct errors (H09) presented severity approximately 50%. Although this software provide a lower frequency of errors, most of them have high severity and can affect user interaction, particularly for novice users. Finally, in Geotouch, the only problems found were related to system status visibility (H01), prevention of errors (H05), recognition instead of memory (H06) and flexibility and use efficiency (H07). All these problems classified in the heuristics had low severity ranked from 25% to 50% by the experts.
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