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Data structure and algorithm: a visualized web based courseware improves cognitive learning.


The idea of animations and visualization is not new. During the last few decade bundles of new strategies in science, medicine, technology, multimedia, education and even in learning have been developed. Our study presents an analysis, evaluation and design study in the domain of computer based learning. It is a multidisciplinary field which is investigating the design of user friendly computer learning systems and platforms. The term cognitive or cognition relates to psychology, Cognitive is all about the mental abilities which are related to knowledge, problem solving and decision making, as it was published by Shivani and Deepak in 2014 [1]. There is a major relationship between educational policy makers, public, parents and the teachers; to analysis the important factors to influence student achievements. For example, effectively delivered high quality knowledge can be a main factor to influence the student's outcomes [2]. To learn different things consciously, we always use cognitive abilities. In cognitive we use previous knowledge and techniques to perform different tasks in practical life. In the field of psychology the concept of cognitive learning directly relates to the mental thoughts and intelligence [1]. So if consider learning then the visualization is very important term for learning knowledge. Animations of different problems can make the learning process very easy and interesting [1]. It's a technique which enables learner's consciousness, abilities, and perceptions to motivate them to gain knowledge [5]. Graphic representation, such as pictures, graphs, charts and diagrams help people to get the meaning and understanding of information more easily and quickly as this cognitive study was published by Lewalter [3]. Computers have been used for drawings, graphing, chartings, visualizing and animating purposes in the last few decades.

A recent study on animation have done by Barbara and Morrison, that children always show much interest on watching cartoons than reading story books [5], because cartoons affects like a real time environment. Meanwhile it increases children's learning process and helps to build their perception cognitively. If we talk about animations and visualizations, Kumiyo and Nakakoji did a research that it works cognitively in analyzing of exploratory visual data [11]. Animations can be developed and implemented in any field, for example in business department for intelligent decision making [7], in education department for better learning and in medical department for better treatment etc. But in our research, we have focused education department and we have tried to develop and visualized a very important course of computer science called data structure and algorithms. After development of prototype we implemented this prototype application in a real time environment i.e. classroom. During our lectures we let students directly interact with this application. Animations and visualizations provide an attractive environment to learner, for actively exploring algorithms [4]. Algorithm visualizations applications have been widely viewed in technology, as these applications are having the potential for good impact in computer science education [19].

However, our research is concerned about the effects of instructional technologies and media that include computer screens, animations, human interaction, learning technologies, and survey about cognitive effects of visualization/animation on education. The way of creating an online educational visualization platform, provides instructors as well as learners the best opportunities to improve the teaching and learning techniques respectively. Most of the visualization applications are on easy access, open source and free of cost. [19]


As we know that the idea of animation and visualization in not new. After an extensive review of the literature of cognitive learning techniques and animation technologies that have made an interaction with education, we have explored and identified many deficiencies in the world of visualization. A recent study on animation by Barbara and Morrison in year 2013 stated that in the past decade, high quality and graphical user interfaces have become a standard, especially in the field of games [5]. We have found that there are different kinds of visualization platforms helping people in different areas of life. Especially in the field of education there are bundles of visualization platform for students about different courses of science and technology [19]. As we know currently the world is moving to E-Learning platforms and people prefer to sit at home and attend lessons online. So as for it concerns HCI (Human Computer Interaction), which is focusing to facilitate teachers and students to provide them the interactive and user friendly interface [5]. The existing new methods and approaches to study algorithms were done by Marc H Brown in his publication of algorithm animations [8]. In year 2003 Rainer Koschke has conducted a survey on "software visualization"; this survey was conducted through e-mails. The survey papers were sent to researchers in software maintenance departments and reverse engineering [6]. These kinds of surveys have conducted and published elsewhere [7], [17].

Keller and Bassil conducted similar survey but this survey was about software cost, quality and little focused on cognitive aspects of available visualization tools [12]. In the literature study of data structure and algorithm visualization, we have found some visualized platform serving students [9], i.e. O-Matrix, Algolist, Jeliot3, TRAKLA2, David Galles (Visualization), John Morris (Visualization), NZACDITT, CATAI, TANGO etc. [9]. There is another good website of data structure visualization was developed by Duane Jarc in the institute of George Washington [13]. A very famous data structure and algorithms online platform was developed by David Galles [14]. There is a very famous learning environment tool TRAKLA2 for data structure and algorithms course [15]. Open DSA, a web platform which provides an active e-book to develop an online text book for DSA [16]. During our research study, analysis and survey, we found some short comings also of these applications as written below.

* The visualization levels are very detailed, so those make a little bit difficult to understand for a beginner student.

* The majority of the instructional sites are lack of interactive multimedia and animations.

* In some web applications java applets always display message to update, even after updating.

* In some platforms an extra code is required to perform visualization, but it requires some technical skills.

* Some surveys were conducted through an email from engineers & professionals of Computer field.

* Step by step working detail was not provided, it makes difficult for learners to understand in detail.


This chapter will briefly describe about the prototype application which have been developed for the offered data structure and algorithm course at ZJUT. And this application was fully implemented in a real time environment like classroom to teach this course.

3.1 Problem Statement

To be working as teacher assistant at ZJUT for the course of "Data Structure and Algorithm", it has been noticed that during lectures some students were facing problems in understanding of this course. Because this course always considered as a very tough course for beginner classes. To facilitate the learners of this course, we decided to develop a visualization courseware to enhance the learning of students and to facilitate teachers in lectures by using this visual aid [1].

3.2 Design Phase of DSA Application

After identifying, exploring, analyzing system complexity, available resources and by considering all risks, the most suitable method for this project was prototyping. We decided to introduce teachers and students the concept of visualization during lectures. It may be very interesting for us to determine whether using visualizations applications can facilitate students, to easily understand the functionality & efficiency of an algorithm. One of the major requirements was to develop a learning platform for students, which is easy to use and attractive.

Here are design phase and detailed flow diagrams.

Figure.1 shows the main architecture of the developed prototype application. It displays that user would directly interact with the application through internet by using any browser. The prototype application has been uploaded to the system, and all the animation and visualization have been performed on internet.

Figure2 shows the detailed flow diagram of the whole system, that how the user can interact with application and would be able to perform different visualizations. There are many predefined function have been declared to perform animations. On front end, a canvas has been used to display all the animations in browser. We have used the main initializing function into canvas. Then all the other functions have been called into main function. With the help of javascript files, we have been performing different animation.

3.3 Development of DSA Course Contents

Our main focus was to design and develop an online education visualization platform, which would be accessible all over the world through www to facilitate learners, secondly to find out the importance of visualization application in cognitive learning. To achieve this goal first we have designed the prototype of course "data structure and algorithms" for the students of ZJUT China. Currently, we have visualizations for the following data structures and algorithms:

* Data Structures (Queues, Stacks) via Link List & Arrays

* Searching (Algorithms and Trees)

* Sorting and Selection (Insertion Sort, Merge Sort, Heap Sort, Shell Sort, Bubble Sort etc...)

* Graph Algorithms (BFS, DFS etc.)

* Tree Based (Heap Data Structure)

* Factorial

There were multiple factors to be considered before the development of this prototype application i.e. time, cost, risks, effort, security and user friendly interface. After considering all these factors we decided to use HTML5 and java script to develop this application. We have designed a beautiful interface for displaying different animation using different control buttons. This interface consists of three parts; the top is header of the website with menus and submenus for switching to different pages. The down part consists on labels and the titles of the running algorithm animation with all control buttons related to that animation. The third down part is the actual part, where all animations run.

Here are some selected snapshots of developed DSA visualized application.


To get the feedback from students about the importance of visualization we used a survey methodology. Method of survey was very simple and very concise. We designed a survey questionnaire that consists of 20 different sequentially related questions. Questions were comprehensive, easy to understand and fully describing the meaning of concerning topic. Initial questions were about student's background knowledge of visualization. Then some questions were about importance of visualization and its cognitive effects on education. The questions in final part were consisting on future trend of learning and visualization application in education sector.

To know the effectiveness of the developed prototype application, we have collected several kinds of supplemental data. All students took an active part in the survey. We conducted this survey in three different parts. The first one was before the demo class of visualized course of "data structure", second survey after demo classes and the third survey from mixed students of different departments & schools. The questionnaire was very simple and consisted on fully optional question answers. The purpose of survey from classroom was to know the difference between the results, before demo classes and after the demo classes. Although the difference was not very big but still results were different in both cases. Some of the students were unaware from these visual. More than 130 students participated in this survey, in which 70 questionnaire forms were filled by the students of course "data structure and algorithm" at ZJUT.

4.1 Survey Results and Comparison

This section will show the results of conducted survey and comparison between these results. For statistical analysis we decided to use SPSS software as an analysis tool. We have applied a standard statistical technique, pie charts for analysis data. Basically we are going to comparison in groups of students who were taking the courses of "data structure"; to evaluate that how they consider about provided prototype application, for learning the data structure course through visualizations. During the demo classes the students feedback was 100%; students were showing interest in visualization, meanwhile we have noted that teaching with visualization tools students would pay much attention on concerned topic and learn attentively. Let's see statistical results of some selected questions.

Note: Each column consists of three different graphs. The first two graphs are showing the results of course "Data Structure" students at ZJUT. The first one is before demo classes and second is after demo classes. The third graph shows result of the general survey.

After collection of all results, we started a comparative study. The results after demo classes of DSA visualization application have a dramatic change. During survey analysis there were two major reasons came to know, that most of the students were never used visualization for study purposes and it was very difficult for students to learn this course of "Data Structure" by using old teaching method i.e. PowerPoint slides or Blackboard. So for these students animated learning platforms were totally new and very attractive. Their responses after demo classes were totally different. This result shows that they got awareness from our survey to use animated learning platforms. Most of the students have appreciated our developed prototype application and ask us to develop these kinds of applications for other courses. Some students have also supported online learning applications, where they can show their presence through internet by video conferencing. They can get all the course materials online. If we consider the overall results of the survey, we can conclude that, most of the students are fully in favor of visualization, because they think that it helps them in study.

4.2 Cognitive Effects of Visualization on Learning

In the study of cognitive effects of visualization application in education, we have realized that, in order to get specific results of computer based learning, it would be very necessary to develop more and more visualized learning applications and tools [1]. From our survey results we can say that online visualization tools are very helpful for learning cognitively. We have been studied many benefits of visualization over the old teaching method. We have also confirmed that interaction with animations and visualizations is an important part which let learner attend class fully attentively. Algorithm animations can also develop a number of valuable & useful contributions i.e. it can describes the models for software engineers to creating animations, for users interacting with animations, script writers to creating and dynamic documents, and for script viewers to directly interacting with these dynamic documents [11].

The present study is fully based on cognitive orientation, which enables the students to take an active part in their learning to get a quality based education [3]. Some modern teachers have been using animations to enhance their teaching method and the outcome of it is really great. They are using the visual aids to enhance the observational attention of learners on a practical work so that their imagination might bring them to the point where they could see things happening real time environment [18].

If we consider survey results of cognitive learning, most of the students were very satisfied by our developed prototype application. The results of the survey before demo classes and after demo classes were totally different as shown in figure5.


The intermediate question has been asked whether this application is effectively used during learning of course "data structure and algorithm". The evaluations have also confirmed that application was very useful for learning this course. Furthermore student's feedback is one of the reasons to make us confident to say that students perceived application as very helpful tool. During the demo classes, students were showing fully interest in this application. Meanwhile they were predicting different further steps of animations. Our research has shown that some of the web based courses those are very easy to use and understand are strongly accepted by students. There are one limitation of developing data structure visual learning platforms is its cost, because these kinds of visualizations are not easy to make, it requires a lot of imagination, hard work and time.


Visualization is a great step in the word e-learning. We have been designed and developed a prototype visualization application of course "data structure & algorithm" and we implemented it, in a real time environment like a classroom. After implementation of this application we have conducted a survey from students in the form of questionnaire. Most of the students appreciated this visualization application and showed a full interest during lectures. Our work and study has answered a set of questions about the effectiveness of visualization and animation techniques in computer based learning. Currently we just have visualized very important course data structure and algorithm, now we are looking forward on other courses of computer science to visualize. While during the analysis of surveys results, we have known that most of the pupils were unaware about visualization applications and the cognitive learning techniques. Even some teachers are not aware too that the use of visualization applications can help students in cognitive learning. They should use the advance teaching methods like visualization or animation applications during their lectures, our developed application emphasizes on providing visual aids to teachers while delivering lecture in class. Meanwhile it provides an online learning platform for students; they can access visualization of data structure course contents online for learning and practice. We believe that these kind of visualization application going to boost a revolution in the fields of medical and engineering [1].


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Junaid Akram and Luping Fang

College of Information Engineering

Zhejiang University of Technology, Hangzhou China

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Author:Akram, Junaid; Fang, Luping
Publication:International Journal of Digital Information and Wireless Communications
Article Type:Report
Date:Jul 1, 2015
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