Jaime Urquiza-Fuentes

Merging interactive visualizations with hypertextbooks and course management

As a report of a working group at ITiCSE 2006, this paper provides a vision of how visualizations and the software that generates them may be integrated into hypertextbooks and course management systems. This integration generates a unique synergy that we call a Visualization-based Computer Science Hypertextbook (VizCoSH). By borrowing features of both traditional hypertextbooks and course management systems, VizCoSHs become delivery platforms that address some of the reasons why visualizations have failed to find widespread use in education.The heart of the paper describes these features and explains, from both a student and teacher perspective, how each feature adds educational value to a visualization. In some cases, this value focuses on pedagogical issues, taking advantage of known strategies for making visualizations more engaging and effective. In other cases, the emphasis is on making it easier for teachers to use visualizations. A set of possible use scenarios and approaches for increasing interest in adopting a VizCoSH are also presented.

An approach to effortless construction of program animations

Program animation systems have not been as widely adopted by computer science educators as we might expect from the firm belief that they can help in enhancing computer science education. One of the most notable obstacles to their adoption is the considerable effort that the production of program animations represents for the instructor. We present here an approach to reduce such a workload based on the automatic generation of visualizations and animations. The user may customize them in a user-friendly way to construct more expressive program animations. These operations are carried out by means of a user-friendly manipulation based on the metaphor of office documents. We have applied this approach to the functional paradigm by extending the WinHIPE programming environment. Finally, we report on the successful results of an evaluation performed to measure its ease of use.

SRec: an animation system of recursion for algorithm courses

In this paper we describe SRec, a system to animate recursion in Java programs. It is intended to assist in algorithm courses to better understand and analyze algorithm behavior. We make several contributions. Firstly, SRec exhibits a comprehensive set of animation and educational features. It provides three complem- entary, coordinated views of recursion: traces, the execution stack and activation trees. SRec allows the user constructing and modifying animations without effort. The animation can be played flexibly, both forward and backwards. It also provides facilities to integrate animations into courses. Secondly, the paper describes the educational features of the system and its use in algorithm courses. Thirdly, the system has been fully evaluated with respect to usability (using formative and summative methods) and has been compared to other systems reported in the literature. The results of both evaluations are highly positive.

Development of XML-based tools to support user interaction with algorithm visualization

As a report of a working group at ITiCSE 2005, this paper represents a vision of the use of XML specifications and tools in algorithm visualization, particularly with regard to supporting user interaction. A detailed description is given of how an interesting event to be visualized is decomposed, combined with interactive questions, narratives, control flow code and metadata, and finally rendered into graphical primitive and transformation specifications. The heart of the paper is our discussion of XML specifications for content generation (the object being visualized), interactive questions, and graphical primitives and transformations, with briefer discussions of narratives and metadata. Examples are provided for each in an appendix, with fuller details to be published on an associated website that we hope will become a source of future standards in this area. In conclusion, the approach of the working group is discussed, and important remaining challenges are identified.

An Evaluation of the Effortless Approach to Build Algorithm Animations with WinHIPE

The use of algorithm visualizations in computer science education is not a new thing. Although there is a firm belief that graphical representations of algorithms are learning aids, empirical studies show that what is important is what the students do with the animations rather than what they see in them. In this paper we compare to kinds of interaction: viewing animations vs constructing animations. We have conducted a controlled experiment where a group of students (n=15) had to study an algorithm and complete a knowledge test about it and a subjective opinion questionnaire. Students were randomly divided in constructing and viewing groups. Results have been measured by means of learning outcomes, efficiency issues and students subjective opinion. Results significantly evidence that builders obtained better results than viewers.

A Design of Automatic Visualizations for Divide-and-Conquer Algorithms

The paper addresses the design of program visualizations adequate to represent divide-and-conquer algorithms. Firstly, we present the results of several surveys performed on the visualization of divide-and-conquer algorithms in the literature. Secondly, we make a proposal for three complementary, coordinated views of these algorithms. In summary, they are based an animation of the activation tree, an animation of the data structure, and a sequence of visualizations of the substructures, respectively.

VAST: visualization of abstract syntax trees within language processors courses

In this poster we present VAST, a visualization tool to support teaching language processors. On the one hand, VAST provides an API that allows generating visualizations of abstract syntax trees (AST). This process is independent of the parser generator. On the other hand, VAST provides an advanced interface to animate the AST construction process and to cope with huge ones.

Effortless construction and management of program animations on the web

We describe an extension of a programming environment to generate web-based program animations. Emphasis is put on requiring little effort from the instructor that handles the system. User interaction is reduced to a minimum, mostly for customizing the animations. Both construction and maintenance are considered in order to guarantee low effort in an actual educational scenario. We describe several aspects of a program animation: the different kinds of information that compose it, its construction process, alternative graphical designs for web publishing, and its implementation as a package. In general, the instructor will wish to use the system to construct and handle a collection of animations for one or several courses. Therefore, we also consider the creation and management of collections of animations in a effortless way. Finally, we describe our experience as well as related work.

An instructor's guide to design web-based algorithm animations

Much research effort was directed in last years to address two key issues in Web-based algorithm animations: lack of evidence of their educational benefit, and the considerable effort put on the part of instructors to construct animations. Consequently, there is a valuable corpus of lessons learnt to design effective algorithm animations, but these recommendations are very general. The designer of an animation has no guide for fine-grain decisions, which often are the basis of a successful animation. The goal of this study is to deepen in these issues by identifying good choices for the number of animations, structure and size of an animation, and size and value of input data. We describe the problem, our hypothesis and our findings, written as an instructors guide for the design of educationally effective animations.

SOTA: a visualization tool for symbol tables

SOTA stands for SymbOl Table Animator. It is an educational tool that allows visualizing the structure of the symbol table during the compilation of a program. SOTA allows the user to view simultaneously the source code of the program, the graphical representation of the symbol table and a list of actions performed on the symbol table by dividing respectively the interface into three areas: the program area, the state area and the messages area (see Figure 1). In the program area, the last token processed is always highlighted; it is synchronized with the state area, where the current state of the symbol table is graphically displayed, and with the messages area where all the operations done until the moment are listed. Also if an operation is selected in the messages area, the related token is highlighted in the program area.