Development of a Web-based Digital Signal Processing Course A Methodological Approach B. Cannone, TEI Piraeus, Dept. of Automatic Controls -
[email protected] Y. Psaromiligkos, TEI Piraeus, Dept. of Mathematics - Computer Science Laboratory Simos Retalis, Univ. of Piraeus, Dept. of Computer Science Dimitris Tseles, TEI Piraeus, Dept. of Automatic Controls
Abstract Within the past few decades, the World Wide Web (www, web) has been expanding at an astounding rate. An area of rapid growth that immediately comes to mind is that of electroniccommerce, however, educational delivery systems operating on the web, e.g. in the form of online university courses, intelligent tutoring systems and educational web-casts do not lag far behind. An area of particular interest to educators is that of Web-based Educational Systems (WbES). Because however, WbES are complex systems that incorporate a variety of organizational, administrative, instructional and technological components, systematic, disciplined development approaches are of great importance [Carlson, 1998]. Nowadays, Web-based Educational Systems (WbES) make extensive use of network technologies, especially the Internet and the www because of their potential in advancing interactivity between learners and tutors, in offering flexibility concerning the mode of learning and in providing easy, one-stop maintenance and reusability of resources. There is an identified problem however. Many systems developed to date, have been done so on a quite individualized, non-standardized, ad hoc basis, resulting in systems that do not fully exploit the advantages afforded by networked technologies and thus lack learning effectiveness [Psaromiligkos and Retalis, 2003]. This paper presents the development and design of a web-based Digital Signal Processing (DSP) course as a case study of a development and design methodology for educational hypermedia applications, i.e. a methodology that specifically targets concerns of critical importance when developing a Web-based Educational Application (WbEA). The DSP course case study presented here emphasizes the development and design of the WbES web-ware subsystem (Web-based Learning Resources Subsystem), which in dealing with the content inevitably concentrates the area of most interest. This paper first presents a brief justification as to why the methodology used was chosen over other methodologies available today, followed by an overview of the selected methodology and last but not least, the details of the DSP course case study itself are presented.
Development Methodologies for Hypermedia Applications There are several methodologies available today for the development of hypermedia applications; however, these methodologies do not directly target Web-based Educational Applications. The exception to the findings of the literature review conducted was the Web-based Courseware Development Methodology for Open Learning Systems (CADMOS) that is detailed in the “CADMOS Methodology - Users Manual” by S. Retalis and G. Tselios (1999), National Technical University of Athens [Retalis, Tselios, 1999].
Of the currently available
methodologies reviewed (e.g. Hypermedia Design Model (HDM), Relationship Management Methodology (RMM), Object-Oriented Hypermedia Design Model (OOHDM), Web Site Design Method (WSDM), etc.), the CADMOS methodology was selected as the most well suited for the development and design of an Educational Hypermedia Application, i.e. the DSP course. Before presenting the details of the DSP course, the following section gives an overview of CADMOS.
The CADMOS Methodology Introduction The CADMOS Methodology is a development methodology for Web-based Educational Systems (WbES) that gives exclusive emphasis to the development and design of the Web-based Learning Resources Subsystem, i.e. the Web-ware. As such, CADMOS can be seen as a development and design methodology for hypermedia applications that specializes in Web-based Courseware. The CADMOS methodology provides a holistic approach to the development; design and implementation of web-based courseware with the aim to fully address the learning objectives of the target course and assure that these learning objectives are met. CADMOS is a documentdriven methodology that begins with the creation of the Requirements Specification in nontechnical terms that will assure that all learning objectives of the course are addressed and provided as input to the development and design phases. This cannot be said about any of the other methodologies that were reviewed as part of a literary survey. By comparison to other methodologies reviewed and mentioned above, while they offer formalization of the design process and guidelines for design activities, for most however, their scope of applications is not broad enough to fully encompass different types of applications, such as educational ones. It is because of the specialization in web-based courseware development and design and the holistic, complete scenario that the CADMOS methodology offers, that is was chosen over other available hypermedia application development methodologies. While this paper presents the creation of a DSP course as a case study of the CADMOS methodology, the flexibility of the methodology lends itself to the development of web-based courseware in any field of study.
Following the Methodology According to CADMOS, the instructional system development should follow three main processes [Psaromiligkos and Retalis, 2003]. These processes are: The Problem Solving Process The System Construction Process The System Utilization Process Additionally, being a document-driven methodology, CADMOS offers a template for the formulation of each of the deliverables that make up the methodology.
Problem Finding Process In accordance with CADMOS, the first process in the development of a WbES is the Problem Finding Process. The aim here is to define the teaching problem that stems from particular educational and teaching needs and as a result of this process, come up with a non-technical solution for this problem. The output of this process is the non-technical or abstract solution, the First Deliverable according to CADMOS. The non-technical solution will describe: what will be taught, with what aims or goals and by what means in order to fulfill these goals. Once this has been accomplished, the next stage will be to translate this abstract description into the actual instructional system. Thus, the nontechnical or abstract solution to the instructional problem serves as the Requirements Specification for the WbES. This specification will serve as the input for creating a “technical solution” or architectural blueprint of the WbES being developed as addressed below.
The System Construction Process The Technical Solution to the Instructional System In accordance with CADMOS, the next step is that the non-technical solution to the instructional problem is transformed into a Technical Solution (Second Deliverable). The abstract solution is separated into four sections that are the basis for the architectural blueprint of the instructional system being developed.
The four interrelated subsystems that make up the architectural
blueprint are the human subsystem, the web-based learning resources subsystem, the non web-based learning resources subsystem and the technical infrastructure subsystem [Retalis and Avgeriou, 2002].
It is important to note here that the CADMOS methodology supports
ONLY the development and design processes for the web-ware or web-based learning resources subsystem of a WbES, which is also the emphasis of this paper. For a detailed look at the WbES
configuration for the DSP course case study that shows just where the web-ware subsystem fits into the entire WbES see [Cannone-Syrcos, 2004]. Once the four subsystems have been constructed, they are then integrated into one “whole” instructional system that is ready for the first pass of the utilization process. As mentioned above, the Web-ware Subsystem is the emphasis of this project and as such will be the point of concentration for the remainder of this paper.
Web-ware Subsystem Development and Design The Development Model According to the CADMOS model, a Web-based Educational Application (WbEA) is a mosaic of learning resources such as hierarchically arranged sets of pages of an electronic book, on-the-fly pages such as ASP or JSP, web testing resources, informative material, discussion topics, etc. The overall scheme is that each of these parts will be assembled together in the end to create the entire web-ware (WbEA) configuration. Each part of the web-ware developed is, however, in itself completely functional. This is the basic difference between the CADMOS development model and other means of developing web-ware that may follow a more haphazard approach.
The Design Method The method of design will describe the details of the web pages that make up the parts of the web-ware, such as their environmental details concerning internal structure, relation to other web pages that make up the web-ware as well as their appearance, i.e. the Graphic User Interface (GUI). The steps that are followed for the web-ware design according to CADMOS-D (Design) along with the product of each of these steps (given in parenthesis) is as follows: •
Architectural Design (Conceptual Model or Schema)
•
Detailed Design and Relational Flow (Navigational Model or Schema)
•
User Interface Design (GUI)
What each design step lends to the methodology will be brought out in the presentation in the followings sections that discuss the details of the DSP course design according to CADMOS (Third Deliverable).
The DSP Course Case Study This section presents the DSP course case study that was developed according to the CADMOS methodology [Cannone-Syrcos, 2004]. The course is designed for third year undergraduate students at the Technological Institute of Greece (TEI), Piraeus as well as any student who
applies and is accepted for the course through the regular administrative system. The following presents the architectural design for the DSP course at the Conceptual level.
Architectural Design at the Conceptual Level At the conceptual level of design, the description of the WbEA is transformed into a “Conceptual Schema” or “Conceptual Model” that follows an object-oriented conceptual design model. This schema is a composite item that illustrates the web-ware as a mosaic of learning resources.
The DSP Course Conceptual Model The Conceptual Model for the DSP course was designed according to the UML notation and is presented in Figure 1 below. This schema presents the Main Application (WbEA) or Courseware that is made up of several parts as indicated by the aggregation relation of the UML notation [Fowler, 2000]. These parts that make up the courseware are the learning resources for the DSP course that were determined in the second deliverable of the CADMOS methodology. The learning resources that make up the DSP courseware including the Home Page are the Syllabus, Didactic Book, Slide Presentation, Assignments, Demos, Past Exams, Case Studies and the Resources/Links. According to the CADMOS methodology and as illustrated in the conceptual model, these learning resources are considered to be either a Concept, or a Composite Concept. A simple concept is just that, a single conceptual entity, e.g. the DSP Syllabus, whereas a composite concept is made up of one or more simple concepts or even composite concepts. Figure 1 shows an example of a composite concept that has as its parts two simple concepts and a composite concept. This is the case of the Didactic Book. The conceptual model for the DSP course presented in Figure 1 thus gives the conceptual architectural design that the courseware will follow. The schema illustrates the hierarchical structure of the web-ware and the relations between the learning resources (simple and composite concepts) as well as the learning resources’ relations with the various types of actual resources, i.e. HTML, Java Applets, Active Server Pages (ASP), Java Scripting and the Power Point. After reaching the point where the conceptual schema accurately represents the desired structure for the courseware, it is then used as a pattern to structure the design work to be done at the Navigational level, i.e. to come up with the Navigational Schema or Navigation Structure Model.
Figure 1. Conceptual Model for the DSP course
The DSP Course Navigational Schema (Navigation Model) The DSP Navigation model is designed to document the navigational structure of the web-ware. The navigational design serves two purposes, one to give direction in the integration phase and two, to serve as a map for future updates to the site, i.e. web page additions and deletions. (See [Cannone-Syrcos, 2004] for details of the DSP course Navigational Schema). Once the navigation structure model was developed to a reasonable degree of satisfaction, the next step was to design the graphic user interface for the DSP courseware as discussed below.
User Interface Design (GUI Level) Background The Graphic User Interface (GUI) is the deliverable of this phase and is part of the third deliverable according to CADMOS. The GUI is constructed to present the structure of the content, the layout and in general will give the ‘look and feel’ of the site. According to the CADMOS methodology, the data model consists of six types of components: plain text,
multimedia elements, active elements, hyperlinks, frames and form elements that are designed such that they are re-usable page templates. This paper presents only one of the GUI templates, i.e. that for the Main Access Pages (Figure 2).
The DSP Course Graphic User Interface (GUI) Templates As the third phase in the design process, six GUI templates were designed for the DSP courseware as listed below. The logic behind creating templates is two-fold. By creating templates, (1) the appearance of the site is under control in terms of the consistency of the web pages that comprise the various learning resources (Concepts) and (2) the graphic user interfaces for the courseware are documented should there be a need in the future for page insertions in any area of the courseware. The six templates designed are templates for the Main Access Pages, Content Pages of Didactic Book, Interactive Exercise Form, Interactive Exercise Solution, Slide-ware (Power Point Presentation) and Demonstration Routine Pages.
Main Access Pages As illustrated in Figure 2, the main access pages are made up of three main tables, a Header Table, a Footer Table and a Central Table. While the Header Table, Footer Table and the LeftHand Navigation Module Table of the Central Table remain the same for all main access pages, the Main Content Section of the Central Table is the editable section that changes depending on the access page. The editable section is itself a table that is the second table definition of the first row of the Central Table. The Main Access pages all adhere to the template illustrated in Figure 3 and are comprised of the: Home Page, Syllabus, Didactic Book, Slide Presentation, Assignments, Demos, Past Exams, Case Studies and Resources/Links.
Header Table
Central Table
Left Hand Navigation Module (Table)
Main Content Section (Table or Plain Text) Editable Section
Footer Table
Figure 2. Main Access Pages Graphical User Interface (GUI) Template Implementation Issues Once the modeling work for the conceptual and navigation structure model was completed, and the GUI template design work had also been completed, the next step was to implement the learning resources that were decided on for the DSP course case study. How each of the learning resources for the DSP course was implemented is presented in Table 1 below. Table 1 Implementation of Web-based Learning Resources Learning Resource Tools for Implementation Course Description (Home Page) HTML Syllabus HTML Didactic Book HTML, Java Applets, JavaScript, Adobe Acrobat® Self-assessment Exercises HTML Exercise Solutions ASP with Visual Basic Script (VBScript) Slide-ware Power Point, JavaScript Demonstration Routines Java Applets, HTML Assignments HTML Past Exams and Solutions HTML Case Studies HTML, MS-WORD Resources/Links HTML
Evaluation Process There are many ways to evaluate a web-based course and in the past, most methods have concentrated on collecting data via post-course questionnaires in order to gain useful feedback for future builds [[Hiltz, 1997]. This form of evaluation, however, facilitates analysis of the course delivery only, excluding the ongoing process of formative evaluation that by definition can help to avoid problems with the course before they occur. In order to evaluate the web-based DSP Course and in accordance with the CADMOS methodology, two evaluation processes were addressed, the Formative Evaluation process and the Summative Evaluation process. The Formative Evaluation is the on-going process that was conducted throughout the iterative phases of development, design, construction and integration with the goal to ensure that each learning resource constructed and integrated was done in such a manner that the learning requirements for the course were fulfilled. Summative Evaluation, on the other hand, concerns evaluating the actual Instructional Delivery of the online course and works towards giving conclusive feedback to the completed system after the utilization phase. Because the DSP course presented here has not been evaluated as yet, we ask the readers to refer to other works on evaluation using the CADMOS methodology [Psaromiligkos and Retalis, 2003].
Concluding Remarks The CADMOS methodology provides a means of Web-based Educational System development that emphasizes and supports development of the web-ware subsystem.
CADMOS offers a
complete methodology to follow that by way of iteration and documentation, moves web-ware development and design from the ad hoc methodologies that have proliferated this area for years, to a well-structured, logical process producing educational web-ware that fulfills teaching goals, is easy to use, is consistent in terms of style and design and perhaps most importantly of all, is easy to maintain. Through documentation, should any change to the site be needed, clear schemata (Conceptual, Navigational, GUI) exist that indicate exactly which resources and actual pages will be affected by these changes and how changes should be made to ensure consistency of the site. In terms of practices of consistency, CADMOS follows well-founded practices in that the GUI is of a consistent nature in terms of style and practice as the user moves throughout the site. After the implementation phase is completed, feedback is again used in order to look once more at the entire development and design process and if needed, make changes that will improve the site for all users. This feedback is provided through the formative evaluation process, a crucial
process that occurs throughout the entire project, at all stages of web-ware development, design, construction and integration as well as at the end of each of the development iterations.
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