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Editor’s Note: This is a detailed and exhaustive review or research and praxis for model online courses based on Data Structures. Interactive multi-media facilitates learner participation for effective learning. Many options are possible in a media rich environment. Practical considerations are discussed in detail, and the concepts and implementation strategies are well worth very close study.

Developing an Online Data Structures Course
Using Authorware

ABSTRACT

The potential pedagogical benefits of online learning are being recognized widely. This is reflected in the widespread development, both in corporate establishments and in academia, of remote labs and academic courses. However, a common feature of online courses today is that they are either in the form of still text only, or interspersed with some applet animations or incorporate some form of video clips that are often of low resolutions and which do not lend themselves to easy navigation by the online learners.

This paper presents our experience of developing a multimedia-rich, learner-friendly online data structures course using Macromedia Authorware, the premier development tool used for developing interactive, media rich solutions for online learning. We note that graphics animations and active learner participation are crucial components for effective online learning. We report how our online course carefully addresses these issues to good effect. We also report results of our students' questionnaires during the first offering of the course. The results show progressive students' satisfaction with the course from the beginning to the end of the semester.

1. INTRODUCTION

The hottest development in using technology for education is the use of the WWW for delivery of course material and student-tutor interaction and there are countless examples of such initiatives world-wide [Sme97a]. The World Lecture Hall [Wor96] is an online repository or listing of such courses; and within the "Computer Science" classification there are already pointers to 109 courses in computer science on offer in various Universities, and computer science is just one of 98 such categories! Most of these courses deliver teaching material organized as electronic textbook or as electronic course notes that the student can "read" at his/her own pace. Some also provide multiple routes through the material, search facilities, integration of text, image, video and interaction, and question-answer tests. We note that none of the six courses on data structures on World Lecture Hall site provides more than the syllabus and electronic form of the course material.

A common limitation of the online course materials we have reached is that they lack a user-friendly environment that an online learner requires. Whereas our results of students surveys indicate that users are in continuous demand for more control on how they interact with the online course material. Our online course attempts to provide a modest solution to this demand by making it possible for our online course users to

We note that students value these controls highly because they enable progression through the course material as fast or as slow as the student wants to go and in an order or sequence driven by the student's own capability and desire. Subsequent offering of our online course after incorporating these user-control regimes increased the course rating by 30%. We are currently investigating how to effectively incorporate even easier navigation mechanisms using sliders and an hierarchy tree along the lines of File Explorer in personal computers.

Our online course project is based on Data Structures. This course is the last of a series of three basic courses (introductory courses according to [CC2001]) offered in the Department of Information and Computer Science. While this course was more challenging to start with, we nevertheless took it first for a number of reasons. First, it was the only course among the three that has not been offered in our transition from imperative to object oriented paradigm. It will require more work to revise, decide the content and then implement it online. Secondly, students taking the course are already quite familiar with the Internet and so have no learning curve to climb in using the delivery tools. Also, these students already had a computing culture with the use of PCs being an integral part of their daily lives (Our survey shows 98% of the students own PCs).

The remainder of this paper is organized as follows. In the next section we outline the course content development process. Section 3 discusses the issues of animation, recording and synchronization. Section 4 presents the design of our presentation template using Authorware. Section 5 presents how the course material is uploaded onto WebCT and in Section 6 we present our course delivery method. In Section 7 we discuss results of our students' surveys. Finally, we summarize in Section 8 and conclude with acknowledgements in Section 9.

2. CONTENTS DEVELOPMENT

The success of this course is, to a large extent, attributable to the organized and systematic way in which the course content is developed. The course content is developed continuously in a cycle of preparation-presentation-feedback-preparation before the material is in its final form for transferring to the presentation template.

Right at the start of the course development, we planned that each project member will present to the group, in each weekly meeting, two-lectures worth of his prepared content. Each presenter receives detailed comments on various aspects of his presentation including content, choice of examples, contents organization and nature of animations suggested. The overall flow of the presentations is also checked to ensure smooth transition from the lectures prepared by one instructor to another. We also ensure that subsequent lectures build on examples in earlier lectures as much as possible.

One of the important requirements of an online course is engaging the learner in an active way. In an attempt to achieve this, our lecture units contain an average of two pop-up interactive quizzes that seek to test learners' comprehension of the content. The quizzes were developed using Authorware's knowledge objects tool. Various kinds of questions can be created using this tool to minimize the tendency to feel `lonely' that is characteristic of an online course.

Review exercises at the end of each lecture material are designed and tailored to re-enforce students understanding of the relevant material. The laboratory material is developed hand-in-hand with and compliments the lecture material. As the laboratory session is the most important component in the course with respect to skills building, homework questions are designed to enable students to build on the laboratory coverage. This provides the potential for concretizing the students’ skills and building their confidence for independent self-study.

From the foregoing discussion, it is clear that the time investment during content development is high. Content development, voice transcript writing and content transfer to the presentation template amount to about 40% of the online course development time. We believe that this investment is worthwhile in order to produce duplication-free, tightly coupled lectures, labs and homework contents. An immediate consequence of this is the instructors' ability to present, within the same coverage time, and without overwhelming learners, about 25% more material in the online course than in a traditional face-to-face course offering.

3. ANIMATIONS, RECORDING AND SYNCHRONIZATION

One of the most important aspects of an online course is that it should be illustrative. This point cannot be overemphasized. An online course should use multimedia elements (animations, sound, graphics, color etc) in a measured way to illustrate and explain important concepts. As mentioned earlier, animation decisions (what to animate and the nature of the animations) are best done at content preparation time.

Multimedia allows a variety of learning style preferences to be accommodated. Learners can choose to study course contents in a way that suits their preferences with the opportunity to control their pace. With judicious use of multimedia, an online course author can really appeal to learners intuition and, potentially, do better than what can be done in the traditional face-to-face method of instruction.

Using Authorware's animations capability we are able to animate algorithms on trees, graphs, hashing and data compression, amongst others. It is instructive to note that algorithms, which are otherwise cumbersome to teach effectively in a single traditional lecture session, have been successfully animated and effectively packaged to be learned in a fraction of the traditional face-to-face coverage time! Not surprisingly, students’ performances at examinations demonstrate good mastery of such animated algorithms.

A major cost of animations is development time. We note that examples like AVL tree operations, Dijsktra's shortest-path computation and Huffman coding can each take a whole day to animate well. This is partly because Authorware gives full control on animations so that, for an animation element to stand alone, it should be in a separate icon and its movements and transition effect must be set individually. Although animations could be incorporated into Authorware presentations from external sources, the fine granularity of animation elements may not be possible especially since these animation elements may have to be synchronized with voice elements. In our development experience, animations account for about 30% of production time.

If an online course is to include voice, then the issues of recording software, recording format, recording environment and synchronization have to be carefully considered. After trying a few voice editors we settled for Sound Forge, from Sonic Foundry, as our recording software. The choice of a recording format is a trade-off between quality and space requirement. We found that a 16-bit, mono wav file at 98 KHz saved in PCM format produces acceptable quality sounds. Recording should be conducted in an environment in which background noise has no effect on sound quality.

Synchronizing multimedia components must be done carefully. Animation and sound require a certain length of time to play-time that can vary from computer to computer [Macr01]. It is crucial to make sure that these components start and stop at the right time when they are played together. Otherwise the presentation will not be smooth. Authorware provides two functions SyncPoint() and SyncWait() to synchronize sounds with display text and graphics. Synchronization using these functions usually requires repeated testing to determine how long each component takes to load and play. Where any noticeable pauses occur when a component is loaded into memory, the start and stop points must be adjusted for each component.

Our synchronization alternative to using the above functions is to break our sound files into smaller units as dictated by the corresponding text and/or graphics that the sound segments explain. The associated text/graphics and sound segment are then played concurrently or sequentially as desired. This provides an additional low-level synchronization control and makes the presentation more susceptible to future enhancements.

Recording, synchronization and packaging our course material for delivery onto the Web accounts for about 25% of the course development time.

4. PRESENTATION TEMPLATE DESIGN

Before presenting packaging and delivery to the Web, we highlight the issue of designing a presentation template. There are two major issues here: the presentation template itself-its size, color and font styles and size-and the navigation options to be implemented.

When designing a presentation template, the developers should consider carefully the kinds of machine that their clients will be using in order to arrive at a correct size. A template size of 640 by 480 is likely to cater for most computer screens in use today and we use it as a good common denominator. A sample page of our presentation template is shown in the appendix.

We chose and implemented standard navigation options found in typical GUI-based systems. Each subtitle in the front page of a lecture is a link that leads to the first page on which discussion of that point begins. At the bottom of the presentation template are different navigational buttons and sound/presentation control buttons. The navigational buttons enable the students to move to the next/previous page, move to the next/previous section, repeat the current page, move to the beginning page of the lecture and to search for a particular phrase in the lecture.

From our experience in this course, there is demand from students to have more control on navigation through the material. We are considering adding inter-lecture links and a slider to give additional control on navigation. A sample page of our presentation template is shown in the appendix.

5. UPLOADING ONTO WEBCT

At this point all the technical issues of course development have been completed. We are now ready to compile and upload the material onto the Web.

Before uploading to the Web the wav files produced during the recording process should be compressed for increased efficiency. Compression and conversion formats may depend on the authoring tool used. Working with Authorware, we converted our wav files to Shockwave format. Shockwave Audio is a technology that makes sounds smaller and plays them faster off disk or over the Internet. Shockwave Audio can compress sounds up to a ratio of 176-to-1. It also makes them streamable - meaning that they can begin playing before they're completely loaded into memory.

The streaming technology of Authorware enables a presentation piece to be packaged especially for the Web so that it can be efficiently downloaded over the intranet or Internet from a compatible browser. Streaming consists of a packager and a player. The packager prepares the piece and breaks it into segments for faster transmission over the network. The packager also creates a map file that tells the web player what to download, when to download it, and where to put the downloaded segments. The web player manages the downloading according to the map file and runs the piece independent of the Authorware application.

After packaging the course, it is uploaded onto the Web under the WebCT course delivery tool. WebCT contains a rich set of tools for managing communication, student tracking, assessment and tools for conducting and analyzing surveys. Because an online course requires periodic review and enhancements, we take advantage of these tools to monitor the course for future improvements.

6. COURSE DELIVERY

As we mentioned earlier, our online course goes beyond the common provision of many online courses of mere electronic form of the course material. Our course provides much richer course material that is both user-friendly and multimedia intensive. Although the course could be offered as a replacement for lectures in the traditional brick-and-mortar teaching environment, it is currently offered as a compliment to the latter. The course is intended to replace the traditional face-to-face delivery method in the near future. The traditional three-hour weekly teaching times are replaced with a single weekly tutorial hour. Being a four-credit course, the laboratory component is maintained as a traditional face-to-face weekly meeting with the students.

The tutorial sessions are blended into our delivery method to increase personal contacts between the students and the instructors. It is important for us to address the social consequences of students not attending class as part of a large group and we do this with group tutorial sessions that provide an opportunity for socializing, brainstorming and chance conversations. In these weekly sessions students meet the facilitator to discuss and clarify course material for the first twenty minutes of the hour. The remaining part of the hour is devoted to either a quiz or discussion of the quiz taken during the last tutorial session. Students' tasks alternate between taking a quiz and homework submission during the weekly face-to-face sessions.

The laboratory face-to-face meeting is one of the most important components of the course especially in building the students' skills. The laboratory tasks are more or less a do-it-yourself exercise for all but the below-average students. The laboratory documents, like the course material, are carefully written to reflect and reinforce the understanding of the course material. The laboratory sessions are often started with short quizzes on the material to be covered in the current laboratory session. The reinforcement of material in the tutorial and the laboratory sessions leads to a broader skills base with students taking more control of their learning activities. In our mode of delivery, tutorials assume a more important and central role than otherwise as they become the major point of contact among students and between students and lecturer.

The obvious benefits that a series of online lectures have are that students take control of their own learning and do so at their own rate, albeit moderated by the facilitator in charge of the course. The passive transfer of information as in conventional large-class lectures is replaced by personalized delivery, with the student determining when, what, how fast, how much and how often material is covered.

The content of the course is organized into forty lectures as would typically be presented in the traditional face-to-face lecture method. The content of the course has been gathered into lecture-sized units for easier navigation. Each lecture takes, on average, 35 minutes to complete when viewed with the full audio explanations and animations.

As a supplement, the students are also provided with paper copies of the screen dumps of the Authorware presentation for off-line study. The students make use of the hard copy to write additional notes that they transcribe from the online presentation. The course material is uploaded onto WebCT is password protected and each student is provided with an account with which to enter the course page. A CD is also provided containing the compiled course material as posted on WebCT. For online study of the material in the college laboratories, students are provided with walkman-style headphones so as to reduce disruption in the laboratories caused by audio over speakers.

7. STUDENTS FEEDBACK

Following Smeaton [Smea97a], we evaluate our online course according the following three criteria:

The performance of students is a measure of how well they have learned from the online versus the traditional mode of lecture delivery. Since performance in examination is not an adequate measure of comparative students performance (because of varied learning capabilities of students from one semester to another, relative difficulty of examinations, etc.), we relied mainly on our teaching experience and feedback from instructors teaching courses that require this online course as prerequisite. Experience of instructors who taught this course earlier in the traditional face-to-face model found that online students demonstrate a much deeper understanding of the course material. This is partly due to the relatively more active role that students play during online learning. Furthermore, feedback from instructors teaching advanced level courses showed an increased satisfaction in the level of students’ performance as a result of their background in the basic courses.

We analyze the usability of our online course system using the 5 criteria due to Nielsen, [Nie193]:

Overall, results of our students’ survey of the online course are encouraging. Surveys are conducted at the start, in the middle and at the end of the semester. The results indicate increased students' satisfaction through the semester. Early in the semester, about 60% of the students indicate that they were worried and about 30% say they oppose the methodology. In the last set of questionnaires, however, about 60% of the students say they are extremely satisfied, 30% moderately satisfied and about 5% said they were not satisfied at all.

The final aspect of the evaluation of our work concerns the scale of investment needed to create and maintain online lectures. As mentioned earlier, the course material is hosted on WebCT for which there was an existing administrator before our online course. The WebCT administrator is responsible for creating students accounts and troubleshooting the system.

The big investment in creating the online lectures has been the time required. Six instructors worked almost round-the-clock for about three months to produce the first online course. The same instructors worked part-time for three months in the first review period of the course. There are now ten students working part-time on the revised course and comparing it with the version they studied. The students are also exploring the authoring tool, Authorware from Macromedia, with the view to help the instructors cut development time for subsequent online courses.

Other costs include the cost of the Authoring tool, cost of headphones for students and cost of backup hardware. Although each of the course instructors meets the students once in a week, the instructors put significant amount of effort in the online course delivery. In addition to frequent quizzes and homework, the instructors have to respond to students’ questions online or through WebCT's chatting tool as well as conducting and analyzing questionnaires.

In spite of the above costs, online course offerings have, potentially, a number of benefits. First, an online course provides opportunities for training students to be more independent learners, better time managers and ultimately able researchers. Online courses also lead to significant reduction in classroom space usage since the face-to-face meeting time is reduced from three times in a week to only one. Another attractive feature of online courses is the potential of being scalable at relatively low costs. Another important factor is fame; the authors' university is becoming a pace-setter in this important area of online education. Many other universities in the Kingdom and the region at large are showing interest in what has been learned already from this experience.

8. SUMMARY AND FUTURE DIRECTIONS

We have presented the design and implementation of a media-rich, flexible online data structures course, which, to a large extent is unique in its kind. This is partly because the course has gone beyond the traditional online courses that typically consist mainly of still text presentations. Our online course also supports learner interactivity and cater appropriately to the needs of the fast as well as the slow learners; the user can pause, disable voice explanations, repeat a certain point and jump within a lecture as and when needed.

We have also discussed the important role that animations play in an online course. We described how we created effective, reusable animations that are fundamental to illustrate important concepts. Each lecture unit consists of two short pop-up quizzes, on average, that play the double role of making the learner participate actively in the learning process as well as test learner comprehension of the content.

We have also reported in this paper results of students surveys on the usability of our system and the effectiveness of the animations and navigation options. The overall results are very encouraging as they indicate increased students reception of the course through the semester.

As with every online course development effort, we plan to put in place a continuous review regime of improving the course content. Before the next offering of the course we plan to interchange placement of some materials, incorporate additional solved examples and additional drill questions. We also plan to add a navigational slider and a keywords search facility as additional forms of user navigation and control.

9. ACKNOWLEDGEMENT

This research was carried out under the auspices of a University project in the King Fahd University of Petroleum & Minerals. We acknowledge the foresight of the University authority for funding such projects.

We also acknowledge Bruno Press, author of Data Structures and Algorithms in Java using Object Oriented Design Patterns. We made extensive use of the idea of presenting data structures in a unified way as facilitated through the use of design patterns as espoused in this book.

Finally, we acknowledge the efforts of our colleagues in the Online Project with whom we have shared ideas and whose other engagements could not enable them partake in the writing of this paper.

REFERENCES

1. Smeaton, AF and Crimmins, F (1997a), Virtual Lectures for online Lectures: Delivery using ReadAudio and the WWW, in Proc. Ed-Media/Ed-Telecom, Calgary, Canada, 1997.

3. Chang, C et al. (2001), Computing Curricula 2001 (Computer Science), Final Report, December 15, 2001.

6. Using Authorware, Macromedia, Inc., 600 Townsend St. San Francisco, CA 94103, First Edition, August 2001.

Collisions and Collision Resolution Schemes

+ Introduction to Collisions

+ Collision Resolution Techniques

+ Separate Chaining

Quiz 1

-- Open Addressing

Linear Probing (Linear Search)

Quadratic Probing (Non-linear Search)

Rehashing (Double Flashing)

Random Increments/Decrements

+ Quiz 2

+ Review Exercises

f3 sound i ^f pause page 1 of 15

About the Authors

Sahalu Junaidu is an Assistant Professor of Computer Science. He received his Ph.D. from St. Andrews University, Scotland in 1998. His areas of interest include parallel computing, computer networks and e-Learning. He has been a faculty in the Information and Computer Science Department of King Fahd University of Petroleum & Minerals since 1999. He has been co-leading an online course development team for the last 14 months.
Contact Sahalu at sahalu@ccse.kfupm.edu.sa

Jarallah AlGhamdi is the Dean of the College of Computer Sciences and Engineering at King Fahd University of Petroleum & Menials. He received his Ph.D. in Computer Science from Arizona State University in 1994. He worked in research in software engineering and in particular in software metrics. He worked in computer science curriculum development and is working in e-Learning extensively in the past two years.
Contact Jarallah at jaralla@ccse.kfupm.edu.sa.

Developing an Online Data Structures Course Using Authorware