Dr. Tim H. Murphy
Assistant Professor
Texas A&M University

Dr. Kim E. Dooley
Assistant Professor
Texas A&M University

Leah Wickersham
Graduate Student
Texas A&M University

Jennifer Parlin
Graduate Student
Texas A&M University

Background

Many events have recently been broadcast on the Internet though what has come to be called Webcasting. There have been interesting events from the field of medicine, including the birth of a baby (http://www.abcnews.com/sections/living/DailyNews/netmom980610.html), and open-heart surgery (http://207.87.15.72/liveevents/openheart/ f_main.htm). NASA generated quite a crowd with the Mars Pathfinder Mission (http://mpfwww.jpl.nasa.gov/) and John Glenns return to space (http://www.foxnews.com/scitech/space_mission/video). Rock concerts, auto races, and various marketing events, like the launch of Windows 98 have drawn a lot of viewers. Several celebrities, including the actor best known as Captain Kirk, have recently discovered the Internet as yet another outlet for their marketing and personal promotion efforts. More and more, the web is being seen as an additional channel for the broadcast of events captured in digital audio and video.
According to Multimedia Research Group, Inc. (1998) of Sunnyvale, CA, and Fuji Keizai USA, approximately 4,000 Web sites offered video clips in 1996. That number tripled to 12,000 in 1997 and is expected to triple each year for at least the next three years. While this rate of growth is impressive, those 12,000 sites represent less than 1% of the sites on the Web.
Universities and corporations all over the world are considering Web-based solutions for delivering training and information. This delivery would be facilitated through the inclusion of audio, video, and graphic media.
Internet-based training has many of the same positive features as computer aided instruction (CAI). Users can progress at their chosen schedule and pace, have the opportunity to review content at any time, and need travel no further than their desktop computer. Users often retain more when presented with an interactive, multimedia experience. While computer aided instruction (CAI) has long benefited from this principle (Paden and Barr, 1980), the Web was unable to support the bit rates necessary to enable these kinds of media. Video, and to a lesser extent, audio files were simply too large to transmit via the Web.
Web-based training offers inexpensive content creation and management, as well as distribution thats as easy as placing the content on the network and having users open their Web browser to connect to the material. The content remains live on the Web site and is accessible at any time to learners. The interactivity or the Internet can be used to contribute to instruction and allows for user input to help determine the effectiveness of the content.

Describing NetShow Streaming Media:

Windows NT Server NetShow Services is designed to serve content created using a digital file format called Active Streaming Format (ASF). ASF is storage-and-transmission file format that encapsulates multimedia data types. The data types supported continue to expand. Currently, digital images, audio, video, and embedded text can be included. This embedded text can include menu items, scripts, or even URLs to call additional resources. ASF allows the synchronization of these objects within a stream. When you create content for NetShow Services, you create ASF files, or streams.
ASF allows content to be delivered to the client as a continuous flow of data with little wait time before playback begins. For example, a user can spend more than 40 minutes to download an uncompressed digital video (AVI) file thats 40 seconds long over a 28.8 Kbps modem. It would be virtually impossible to deliver standard lecture presentations, which typically run 30-50 minutes per segment. When that AVI file is compressed and converted to ASF, it begins playing after only a few seconds. The file can be of virtually unlimited length, and can run over Internet bandwidths.
Bandwidth remains a limited commodity, and there is good cause to be wary when you begin to work with audio and video - even when you plan to stream your content. However, if you plan your content wisely, you can deliver a really rich user experience, even over Internet bandwidths.

Method

This project was an attempt to chronicle the development and use of a streaming media lesson from the perspectives of the producer, the instructor, and the students. Once the lesson was converted, two graduate students, who had previously experienced the same lesson in a videoconference class, were asked to evaluate the effectiveness of this media. Reflections from each perspective were shared and a qualitative summary provides insights on the appropriateness of streaming media as an instructional strategy.

Results

The Producer

Selecting a Media Type:

Lets examine the types of streaming media one can create using NetShow Services. While others use more and different classifications, I contend that there are only three basic types of files you can produce using any of these products; Video, Audio, and Synchronized Audio. Video and audio files may be streamed either live, as the event occurs, or from an archived file saved to the NetShow server. The process of creating synchronized audio files makes them suitable only for archived streaming.
Video files are the newest, and get all the attention. From a basic perspective, video files include both an audio signal and a series of images played back as rapidly as possible. While new compression and decompression (codec) techniques included with streaming technologies make these files much better than was possible even a year ago, with greatly enhanced audio and much better video quality, the resulting video experience is still no where near VHS tape. The typical streaming video is small (160X120), and the frame rate is typically between 8-15 frames per second (fps). While video compression techniques have improved, and we can now make tradeoffs between the clarity of the images displayed and the frame rate, it is the audio quality of these video files that has experienced the most dramatic improvement. Software developers have come to realize what many of us already knew. In the complete multimedia experience, audio is often more important than video.
Audio files have been available longer. They are inherently smaller in size, and compression techniques for audio have been found that work very effectively for each of the different types of audio. A symphony orchestra has more variability and requires a much greater dynamic range than does a single person speaking. Codecs have been developed to address these differences.
Synchronized Audio files are not really new in concept. I suspect that most of us have experienced an annotated slide show using a 35mm slide projector and a cassette tape. With the advent of client-side processing in web browsers using scripting languages like JAVA or VBScript, these types of media presentations became possible on the web. In effect, an audio file is streamed to a client and embedded in that audio file are commands that cause other types of media to be downloaded and displayed on the client machine. These images or text messages can be embedded in the stream and rendered in the MediaPlayer or they can be URL flips, or commands that cause an image or html coded page to load to a target frame in the client browser.
While perhaps not perceived as state of the art, Synchronized Audio files have several attractive characteristics for distance education and training environments. In terms of the necessary bandwidth, illustrated audio presentations are a step up from streaming audio and at least one step below streaming video. If you anticipate that your target audience will have lower bandwidth capabilities and your content will benefit from illustration, then synchronized audio may be a viable solution. Even when you can determine that your learners have access to higher levels of bandwidth, you may choose to use higher-quality, less frequent, still images rather than poorer-quality video. If you remember that a second of broadcast quality video is really a collection of 30 images shown in a rapid sequence, then the question becomes, do you really need all those pictures?
This is not a rhetorical question. One of the fundamental principles of instructional media design may be obvious, but I think it bears repeating. Each aspect of instructional media (graphics, sound, video) can aid learning, it can be neutral, or it can detract from learning. Although it is very easy to become enamoured with the gee-whiz aspects of motion video at 30 fps, the focus must be its effect on learning. In my experience, and in most of the settings in which its employed and evaluated, visual motion by itself has little effect on learning (Reiber, 1994). In some specific cases, such as when the underlying instructional objective includes motion (e.g. Newtons Laws of Motion), or when used to direct the attention of the learner, putting visuals in motion does contribute to learning and retention. I suggest that you use motion only when you believe it will contribute to your learning objectives, and not just because its technologically possible.
Once youve selected an appropriate delivery media for the transmission of your instructional material, its time to get the hardware and software configured to create your streaming file.

Setting up NetShow:

There are two primary components of NetShow Media Services. NetShow Tools includes the software necessary to create and edit ASF files, and NetShow Server adds a service to Windows NT Server 4.0 that serves, or streams, these ASF files.
Setting up NetShow Tools: 1. I chose a Windows95 machine to accomplish the encoding function. This happened to be my laptop machine, a Gateway Solo 9100 (PII 266/128MB of RAM). The recommended minimum hardware configuration for Win95 is a P133/32MB RAM. I also installed the software on a Dell Optiplex GX1 (PII 400/192MB of RAM) desktop computer running Windows NT. When not encoding ASF files, these machines do all the others things theyve normally done.
2. The laptop shipped with a videocapture card (one of the reasons I chose it). I installed the Microsoft recommended Winnov VO Video Capture Card in the desktop machine. This card is getting very popular in live streaming environments and is giving the other recommended cards (Intel Smart Video Recorder III, Osprey-100) some serious competition at a lower price.
3. I installed the NetShow Tools software, downloaded from the Microsoft Web site, on both machines. Following this installation, I connected my camcorder to each machine, then ran the encoder from the Start/Programs/NetShow Services/NetShow Encoder menu. In both cases, the Encoder found the video source without incident.
Configuring the NetShow Server: 1. Select an NT Server 4.0 machine as the NetShow Services box. Win95 does not support the NetShow Server Services. The NT 4.0 server in my office (PII400/128MB of RAM) also had IIS 4 installed and had been running as a Web server. Microsoft recommends running separate machines for these two services (IIS and NetShow), but supports running both on the same machine, and Ive not experienced any difficulties thus far. I recommend locating the NetShow server and the Encoder machines on the same LAN when possible.
2. Install the NetShow Services software by executing the NSSEVER.EXE installer, downloaded from the Microsoft Web site. Following the installation, select Start/Programs/NetShow Services/NetShow Administrator.
3a. If you want to serve archived ASF files, youre practically finished. Place the encoded ASF files in the proper root directory (default is C:\asfroot) and theyre ready.
3b. If you want to serve or broadcast live ASF streams, there is another step. Create a Broadcast Unicast Publishing Point (easy to do via a NetShow Administrator wizard) linked to your NetShow Encoder machine. This publishing point remains active after you close the NetShow Administrator. The wizard also creates HTML code for use on your Web server. Performing these three basic steps engages the NetShow Services machine in the archived or live Webcasting operation.


Using NetShow Tools:

The NetShow Tools are installed on the machine that takes the audio and video signals, digitizes and compresses them, and provides them to the NetShow Server for distribution. Using these tools, either alone or in combinations, you create and or convert streaming content (NetShow Services, 1998).
The Encoder is the primary workhorse of the NetShow tools package for creating live ASF streams. Compressing live audio and video in real time is an extraordinarily processor-intensive task. The Encoder should be on your best machine, and should be solely dedicated to this task. No unnecessary services or programs should be running while the Encoder is operating. Its counter-intuitive to me, but the higher the target data rate, the higher the processor requirements. For example, if youre encoding live video targeted for 56-Kbps consumption or higher, Microsofts recommended machine is a Dual Pentium II 233 MHz or DEC Alpha 533 MHz. The same video source targeted to a 28.8 Kbps stream, the recommended machine is a Pentium 200 MHz. The Encoder always creates an archived file of the live stream, so it can be used to create archived ASF files, but other tools may be more appropriate. When creating archived content, hardware requirements are greatly reduced because the operation no longer need occur in real time.
The rest of the tools provided are used to create and edit archived files from various sources. The primary workhorse of this team of software products is the T.A.G. Author. To create archived ASF files using the T.A.G. Author you begin by selecting or creating still images and audio files. You then insert these into the T.A.G. Author. You can then sequence the audio and video files, add text and menu itemscalled markers, and insert URL calls to other html pages that will render to a target frame on the same web page as the embedded Media Player.
The PowerPoint Publish to ASF wizard is the simplest path to creating streaming Synchronized Audio files for those already familiar with PowerPoint. If PowerPoint 97 is already installed on the machine to which you choose to install NetShow Tools, the Publish to ASF command line is added under the Tools menu of the PowerPoint program. You can use the Record Narration command under the Slide Show menu of the PowerPoint program to record audio that will be associated with each slide as you advance through a slide show. After saving this file as a PowerPoint Presentation, you simply select Publish to ASF from the Tools menu and the presentation is encoded to your chosen target bandwidth (e.g. 28.8 modem). Your PowerPoint slides, whether primarily text or graphics, will be synchronized with your audio annotation and ready for streaming to your learners Media Player.
NetShow Indexer allows you to edit, in a very limited way, existing ASF files. You can shorten or cut an ASF file and insert or edit markers or script commands. For the most part, you will not want to consider ASF as a format suitable for editing. To accomplish edits of any real substance, the original, or source materials will need to be saved and recreated using another tool like the T.A.G. Author.
The VidToAsf and WavToAsf programs are useful for those who already have powerful programs for editing and compressing, respectively, video and audio files. Neither of these programs is intended for the inexperienced multimedia content creator. Properly prepared video and audio files, created in another software program (e.g. Adobe Premiere, SoundForge) can be converted to ASF format using these utilities. While basic, these utilities are powerful. For instance, markers and URL flips can be inserted in the stream, and an external audio file can be used to replace the audio file associated with the .avi video file.
There are also some third-party tools available that can help speed the processes or provide enhanced functionality. One of the most complete third-party solutions is VivoActive Producer 2.0 for NetShow (Vivo.com, 1998). This $695 product provides a more user-friendly interface to creating NetShow ASF files. The company states that Producer 2.0 for NetShow is your one-stop, total solutions package, and the first and only single application that allows you to generate both live and on-demand streaming media in Microsofts ASF file format.
Before I spent the $695, Id want to try out the, now available and free, Windows Media On-Demand Producer, co-developed by Microsoft and Sonic Foundry. Microsoft advertises that this product simplifies the creation of streaming media content for both experienced and novice streaming media authors (Windows Media, 1998).
Before creating your ASF files, youll want to consider how you want them used and displayed by your users. There are several ways to extend the capabilities of ASF files, and more narrowly define the experience of your learners. These features involve advanced HTML coding, and a basic understanding of scripting languages, but their use can greatly enhance the look and function of your multimedia instructional materials.
For the purposes of this project, the development team chose to create a synchronized audio file from an existing PowerPoint presentation used in an on-campus lecture.

Producing the Annotated Audio Presentation:

The most important part of any multimedia development project is the development of a script. The foundation of a good script is a sound instructional design, and the girders of instructional design are clearly described instructional objectives.
Working from a script, media were collected. While I prefer to collect the audio files first, there is no correct order. The creation of media is becoming easier every day. Scanners and digital cameras are becoming very popular, and high quality audio capture equipment is available for less than $100.
Once collected and digitized as necessary, the graphics will need to be manipulated and resized. T.A.G. Author will utilize .JPG files of any size up to 320X240 pixels. I learned to archive a copy of all visual media in its most original (digital) size and file format. The media may be appropriate for later projects, and will be most useful in its original format and size. I use a recordable CD for this purpose at a cost of about $4.00 per gigabyte.
Audio on the other hand is very sensitive to digital manipulation. Unless handled by an expert, audio quality can be degraded drastically by recompression. For this reason, I suggest collecting, or digitizing, audio files in a file format and at a data rate that is nearly equal to your final target data rate. In my experience, voice is perfectly clear at 11K/ 8bit/ mono. This approximates the final compression rate used by T.A.G. Author when creating a 56K annotated audio streaming presentation.
Once the media have been created, digitized, and manipulated they should be organized. A logical file-naming scheme is helpful. Give files descriptive names, or number them in the order in which they will appear in the final project.
Assembling the final project in T.A.G. Author is a straightforward drag-and-drop operation. Audio is converted or recompressed automatically as it is inserted in the project.
The final step in the creative process is to insert Markers so that the learners can easily skip ahead -- or return to -- the portion of the program in which they are most interested. Previewing the converted media creates an .asf file. Choosing the Publish command creates default .html pages and an .asf file suitable for placing on your WWW server.
Having worked with several multimedia development platforms, I found this one to be very easy to learn. The ability (unused in this project) to embed URL flips and control the users web browser without learning a scripting language (like JAVA) will lend itself to the development of more robust and interactive learning materials by non-programmers.
Both the instructor and I were impressed with the ease with which we were able to create the digital images and audio files, the simplicity of the combination of these files into a multimedia format that can be delivered at WWW bandwidths, and the quality of the final product.

The Instructor


Streaming Media Reflections:

In sharing the faculty perspective, I have chosen to journal my reflections on the use of streaming media.

Monday, December 7, 12:12 p.m.

I just received an e-mail from Tim Murphy with an abstract for the Southern Association of Agricultural Scientists meeting in Memphis, Tennessee. At this point, I had never used Microsoft streaming media and had never taught a lesson in this type of format. Tim came in earlier this morning and discussed the idea and asked for me to think about a potential lesson I could convert. Within a matter of minutes, I thought about a lesson on copyright and fair use guidelines for multimedia development. I use this lesson in both my undergraduate communications course and in a graduate course in advanced methods in distance education. This lesson always spurs discussion and debate, especially at the graduate level. It seemed to be a perfect match for the streaming media delivery mode.
Tim told me we would use still graphics with audio streaming and to make sure I had some snazzy graphics. I typically use PowerPoint graphics, so I had a place to start. He also mentioned the need to script or storyboard what I say in class as I deliver the lesson.
I added his suggestions to my list of things to do and continued with my hectic schedule.

Thursday, January 7, 5:15 p.m.

After finals, graduation, and the Christmas Holidays, I ventured back into my office and began course preparation for spring. That pesky things to do list reminded me that I needed to work on the streaming media project! I printed out the PowerPoint slides Id used in the past, grabbed a couple of resource books, and headed out the door. I normally use scenarios to introduce the topic, so I thought that approach might work just as well in this format. With all my trusted materials at hand, I sat at my desk in my home study and started writing. By this time, it was 9:15 or so, and by 10:00 p.m., I had a script. I simply used a piece of paper and pencil, with a column for the graphic on the left, and what I planned to say on the right. I really enjoyed working on the project and shared my ideas with my husband (while he was trying to watch the news). He commented that this was an exciting approach and he wished he had media specialists/instructional designers to help him with projects like this.

Friday, January 8, 8:20 a.m.

As soon as I got into the office I began looking for Tim so we could work on the lesson. I opened the PowerPoint and made some minor modifications. Once Tim arrived, he said it would only take a couple of minutes to set up the recording studio, and he asked where I wanted to teach the lesson. We decided our offices were too crazy and used a colleagues office that was out of town. Tim set up a laptop computer, with a microphone head set plugged in, and demonstrated how the software worked. By this point, it was 9:15. I started recording, playing back each section and re-recorded if I didnt like how it turned out. This process lasted until 11:00 am. As I was recording, I thought about how convenient it was to be able to re-do things that dont sound okay. Its too bad we dont have that luxury in the traditional classroom!
After the recording session, we coerced students and faculty around us to pose for the scenario photos that I had sketched the night before. We used a digital camera and Tim imported the photographs into the presentation. I put the text-based PowerPoint slides on the share drive and left the rest up to him. By Monday, Tim handed me a diskette of the lesson.

Summary:

A couple of thoughts on the process: I truly enjoyed trying a new way to teach (and a new way to learn). I was surprised at the simplicity and relatively short amount of time it took to create this lesson. Obviously, I had an advantage because I had taught the lesson before and had materials already prepared for synchronous delivery. I also enjoyed planning the script/storyboard to include visual and auditory cues. This approach may prove novel, thus stimulating student interest because of the delivery system. Although I have taught videoconference courses, I am a beginner in the area of web delivery. I see great potential for streaming media, coupled with asynchronous communications (such as threaded discussion groups) to greatly enhance instructional materials delivered at a distance.

The Students

Evaluating the Lesson: Leah Wickersham

As a graduate student, time is the one thing that I never have enough of, and when there is an opportunity to condense the time required to complete an activity, such as a class assignment, thus allowing me time to concentrate on other responsibilities, then I gladly welcome that opportunity. I have had the copyright lesson in both the traditional lecture-based format and via the streamed media. Both methods have their advantages as well as their disadvantages.
During the lecture-based format, the copyright lesson took more time to review-- an hour as opposed to the ten-minute review of the streamed media lesson--with the same material being covered. However, the lecture-based format allowed for discussion among students and the instructor, which hopefully facilitated some critical thinking instead of simply passive learning of the lesson. The interaction with the class and the teacher was something I missed during the streamed media lesson. Yet, I found that the advantage of not attending the lecture-based format lay in my ability to move forward in the lesson as I became uninterested in some portion of the lecture or if I already understood the subject matter being discussed.
Another advantage to the streamed media lesson was that it allowed me to view the material at anytime. If I misunderstood a point made during the presentation, or a concept was not quite clear, then I was able to rewind or pause the media player at any point during the lesson. I found all of the PowerPointðâ slides and still photographs to be relevant to the material being presented, thus creating very little distraction. As I viewed this lesson, I realized that I am not an auditory learner; so there were times I found myself swimming in the material being presented. However, when the screen changed to demonstrate a new situation, or a PointPointðâ slide popped up with new material for me to read, I was back on track with the lesson. I thought that the presentation moved fast enough to hold my attention, but not too fast to where I was lost. I also liked the idea of using the menu to choose particular topics in the lesson to go directly to a spot in the presentation. This ability saves time of having to randomly fast-forward or rewind to find a scene in order to review a lesson.
I do not believe that all lessons should be formatted in the streamed media method, nor do I believe that the creators of the copyright lesson had such an intention in mind. I do feel that some materials lend themselves to be taught through this type of media, and the copyright lesson is one of them. I look forward to seeing more of the streamed media teaching/learning method incorporated in future lessons.

Evaluating the Lesson: Jennifer Parlin

As a graduate student, the material presented on streaming media for class instruction appeared to be beneficial. The eight-minute presentation on copyright material and the hour-long lecture had a few similarities, but the differences are definitely worth consideration.
I tend to prefer the use of the traditional classroom setting for instruction, as opposed to the use of streaming media. This is due, at least in part, to my previous educational experiences and my familiarity with traditional teaching methods. The traditional classroom has, and always will, provide the best form of interaction between a professor and his/her students. Although, this proved to be the only disadvantage of using streamed media, it does seriously impact how a student may or may not benefit from the class. Most students like to feel a sort of closeness with the professor. For example, being able to ask questions at any time and getting feedback is an integral component of the one-on-one method of learning.
Despite the interaction problem, I believe both the professor and student will adopt streaming media in place of classroom instruction for presenting many types of material. Streamed media is easy to access, whether the professor provides it on a disk or posts it to the course webpage, students will be able to start and stop the lesson at any time. The use of streamed media allows the student to pause within a lesson and continue at their own leisure. As I was watching the Copyright material demonstration I received a phone call. I was able to pause the demonstration and start it again later. Some courses, such as web-based courses, are searching for more ways to incorporate interaction. I also believe that the use of streaming media would greatly assist this need and provide a great supplemental tool for any class.
When reviewing the demonstration, I noticed there were a couple of points that both the traditional classroom and streaming media had in common. The information presented was the same and the documentation provided at the end of each was very useful. Streaming media can be a great tool for instructional delivery strategies. The interaction issue is not a barrier to this system, but it is something the professor needs to consider when developing streaming media for instructional use.

Conclusions

In reviewing the perspectives of the producer, instructor, and students, several conclusions emerge. In the area of media development, two components are essential: 1) deciding appropriate content for this type of delivery and 2) planning the script and appropriate visuals. This type of media is easy to create and provides an alternative delivery for lecture materials to be delivered to dispersed audiences. But how do learners respond?
Two graduate students who had received the same lesson (Fall, 1998) in a videoconference delivered course make some excellent comparisons. They liked the ability to save time (and have flexibility with their time) by being in control of the content (able to fast forward, pause and rewind). Accessibility and ease of use of streaming media contributed to satisfaction. Yet, they missed the discussion/interaction typically present in the classroom. Because of learning style preference and familiarity with face-to-face interaction, this media may not be preferred. Both the instructor and producer recognize the importance of interaction in distance education and would encourage a combination of streaming media with electronic mail, threaded discussion groups, desk-top videoconferencing or other communication technologies.
Hopefully you have concluded that successful preparation of streaming multimedia is rooted in precise planning, preparation, systems testing and verification, and an overall understanding of the many variables involved. Few undertakings could be described as more interdisciplinary than the Webcasting of multimedia instructional materials. Of course, the same can be said of many pursuits in Web content development. In addition to content experts and instructional designers, expertise in broadcast production and engineering, telephony, computer systems, and network administration is required. Few individuals hold levels of expertise across such a diverse range of disciplines, so Webcasting is inherently a team effort. Input and expertise will be required from a number of people working together as an instructional development team.
We believe that these techniques can create more robust communications channels for the delivery of instructional media, creating a more effective learning environment for a more diverse group of learners. Should you choose to adopt these methods as a delivery strategy, you will not be alone. Listed below are a few examples of instructional programs being facilitated and or delivered using these technologies.


Examples of Streaming Content:

Cornell University, Dr. Michael Ushay
Medical School Grand Rounds, delivering physicians' lectures to audiences at 20 hospitals.
http://www.microsoft.com/windows/windowsmedia/techshowcase/cornell/default.htm

Stanford Online Course, Doug Brutlag
MIS231 Computational Molecular Biology
http://arum.stanford.edu/courses/mis231/oct12/embed.asp

Stanford Online Course, Kevin Rudd
EE182 Computer Organization and Design
http://arum.stanford.edu/courses/ee182/oct29/embed.asp

North Carolina State University, Rick Klevans
CSC311: Introduction
http://renoir.csc.ncsu.edu/RTCPP/WLS/CLASSES/CSC311/HTML/lect1/start1.ram

Michigan State, Charles Severance
EGR 124: History of the Internet
http://www.vu.msu.edu/preview/egr124/lectures/hist/af001.htm


References

Multimedia Research Group Inc. (1998). Homepage. <http://www.mrgco.com/> [accessed 11/29/1998].
NetShow Services. (1998). NetShow Homepage. <http://www.microsoft.com/netshow> [Accessed 9/15/1998].
Paden, D. & Barr, M. (1980). Computer assisted instruction in an elementary college economics course. Computers and Education. 4, pp. 259-267.
Rieber, L. (1994). Computers, graphics, & learning. Dubuque, IA: Brown & Benchmark.