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Designing a Reusable and Adaptive E-Learning System
A Thesis Submitted to the College of
Graduate Studies and Research
in Partial Fulfillment of the Requirements
for the Degree of Master of Science
in the
Department of Computer Science
University of Saskatchewan
Saskatoon
By
Honggang Wu
November, 2002
Copyright Honggang Wu, 2002. All rights reserved.
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Abstract
The Internet has shown its advantage in e-Learning, a new approach to online education.
It enables online learning materials to be reused by any educational organization around
the world, when there is an efficient way to find the appropriate learning materials on the
Internet and combine them together. The new concept of e-Learning is that by organizing
and disseminating the learning content into a uniform format as small chunks of learning
materials, it is possible to achieve content reuse and interoperation between different
educational institutions and training vendors.
This thesis addresses the possibility of developing learning content based on learning
objects, and evaluates the role played by XML in designing an e-Learning system. The
main goal of this research is to design a reusable and adaptive e-Learning system with
XML schemas forming the basic framework. To implement this goal, the concept of a
learning object is redefined, and a schema for learning objects is developed. Some
modifications to the existing e-Learning specifications, such as the metadata specification,
the content packaging specification, and the learner information specification, are
introduced to make them more suitable for our e-Learning systems. In this thesis, four
online tutorial courses are developed to illustrate how these schemas can work together to
make it possible to reuse learning objects in different learning contexts and to provide
learners with individually tailored learning content.
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Table of Contents
1 Introduction 1
2 Background 4
2.1 E-Learning, a New Way of Learning 4
2.1.1 The Features of E-Learning 52.1.2 A New Approach to E-Learning Content Development 7
2.2 Learning Objects 82.2.1 Background Literature on Learning Objects 8
2.2.2 Reusability of Learning Objects 10
2.2.3 Problems with Learning Objects 112.3 E-Learning and XML 13
2.3.1 XML Schema and its Benefits for Interoperability and Reusability ofInformation 14
2.3.2 XSL, XSLT, and Xpath for Flexible Information Presentation 172.3.3 XML DOM and Java API 182.3.4 Conclusion about Using XML 18
2.4 E-Learning Standards 192.4.1 Standards Initiatives For E-Learning 20
2.4.2 Specification for Metadata 23
2.4.3 Specification for Content Packaging or Course Structure Format 252.4.4 Specifications for Question & Test Interoperability Specification 27
2.5 Summary 27
3 Schema Design 28
3.1 Schema for Learning Objects 303.1.1 New Definition of Learning Objects 30
3.1.2 The Design of a Schema for a Learning Object 343.2 Schema for Metadata 38
3.2.1 The Design of Schema 38
3.2.1 Controlled Vocabulary 41
3.3 Schema for Content Packaging 423.4 Schema for Learner Information 46
4 System Design 49
4.1 Architecture of the E-Learning System 49
4.2 Learning Content Development 524.2.1 Idea and Principles behind Learning Content Development 52
4.2.2 Developing Learning Content 544.3 Design of the Learning Management System 64
4.3.1 Learning Management System 64
4.3.2 Design of the LMS 654.3.2.1 Learning Management Module 66
4.3.2.2 Sequencing/Tracking Module 67
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4.3.2.3 Testing/Assessment Module 68
4.3.2.4 Search Module 684.3.2.5 Learner Profile Module 68
4.3.2.6 Delivery Module 694.4 Summary 69
5 Implementation of the E-Learning System 70
5.1 Learning Content Implementation Details 70
5.2 Implementation of the Learning Management System 755.2.1 Environment of the Learning Management System 75
5.2.2 The Basic Components of the Learning Management System 76
5.2.3 Implementation of the Modules 775.2.3.1 Implementation of the Learning Management Module 77
5.2.3.2 Implementation of the Delivery Module 785.2.3.3 Implementation of the Tracking/Sequencing Module 79
5.2.3.4 Implementation of the Assessment/Testing Module 82
5.2.3.5 Implementation of the Learner Profile Module 835.2.3.6 Implementation of the Searching Module 845.3 System Testing 855.4 Conclusion 88
6 Conclusions 89
6.1 Summary of Thesis Work 896.2 Research Contributions 906.3 Future Work 92
6.3.1 Improving Search Functionality 92
6.3.2 Generating Learning Objects from Databases or HTML files 93
6.3.3 Displaying Learning Objects with Different Formats 936.3.4 Expanding Content Packaging Schema and Learner Information Schema 94
6.3.5 Developing Tools for Authoring Learning Objects and Content PackagingFiles 94
6.4 Conclusion 94
References 95
Appendix A-Schema for Learning Objects 101
Appendix B-Schema for Content Packaging 110
Appendix C-Schema for Metadata 118
Appendix D-Schema for Learner Information 121
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Figures
Figure 2.1 Content Packaging 26
Figure 3.1: Structure of Element 34
Figure 3.2: Structure of Element 36Figure 3.3 Importation of QTILite Schema 37Figure 3.4 Structure of Metadata 39
Figure 3.5 Structure of Content Packaging 43Figure 3.6 Sample Course Structure 44
Figure 3.7: Structure of Element 45
Figure 3.8 Structure of Element 46Figure 3.7: Structure of Learning Information 47
Figure 4.1 Architecture of the E-Learning System 50Figure 4.2 Course Structure for Encryption Tutorial 51
Figure 4.3 Sample Element 57
Figure 4.4 Sample Element 58Figure 4.5 Prerequisite for a Quiz 59
Figure 4.6 Difficulty Range for Learning Content 59Figure 4.7 Learning Object RSA.xml 61
Figure 4.8 Learning Object RSA1.xml 62
Figure 4.9 Sample Metadata 63Figure 4.10 LMS Modules 65
Figure 5.1 Course Structure for Encryption 71Figure 5.2 Course Structure for Firewall 72
Figure 5.3 Course Structure for Network Security 73
Figure 5.4 Course Structure for E-Commerce 74
Figure 5.5 Sample Learner Profile Information 75Figure 5.6 XSL File for Learning Objects 79Figure5.7 System Interface 80
Figure 5.8 Learning Content 81
Figure 5.9 Quiz 82Figure 5.10 Records of Learning Activity 83
Figure 5.11 Changing Learner Information 84Figure 5.12 Searching Results 85
Figure 5.13 Record of Learning Paths for the Encryption Tutorial 87
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Chapter 1
Introduction
As more and more individuals are connected to the Internet, it will penetrate deeper into
our everyday activities, including the way we learn. E-Learning, or Web-based learning is
becoming a new research area in which the web and learning converge on all levels,
whether in elementary school, college, or business. The rapid development of e-Learning
is based on the astounding growth of the Internet and the emergence of new advanced
technologies. For the first time in history people may have access to all kinds of learning
materials 24 hours a day, seven days a week, at any possible location around the world.
The Internet also shows its advantage in course development. For example, if some
educational content, such as a description of computer hardware, is available online, then
it is available worldwide. It could be accessed by each of the thousands of educational
organizations teaching the same topic. Therefore, online learning materials may be easily
reused by many organizations, if there is an efficient way to find the appropriate learning
materials on the Internet and join them together. This is the reason why the new concept,
learning object, has been proposed. The core idea here is that by organizing and
disseminating the learning content into a uniform format as small chunks of learning
materials that are referred to as learning objects, it is possible to achieve content reuse and
interoperation between different educational institutions and training vendors.
In order for different systems to communicate and interoperate with each other, it is
important to have a common language among the systems. Nowadays, the common
language adopted by most learning organizations is eXtensible Markup Language (XML),
since XML can facilitate significant features in the e-Learning framework, such as
personalization, interoperability, reusability and flexibility [XML 2000].
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XML was developed to facilitate the description and exchange of data on the Web by the
World Wide Web Consortium [Goldfarb and Prescod 2000]. It is a means of representing
information according to its internal structure. Such a structure makes the information in
the XML files meaningful and machine-readable, and therefore achieves interoperability
and reusability of information [Bosak 1997]. The great potential of using XML has been
predicted by many developers and technology-driven companies. In fact, several learning
organizations, including a group newly formed by IEEE, are trying to develop e-Learning
standards using XML [Gerber 2001].
However, several key problems remain unsolved for developing e-Learning content based
on learning objects and XML. Firstly, the exact definition of a learning object is still
unclear. Several different definitions exist, and most of them are so broad that they may
lose any useful meaning. Secondly, though it may be possible to find the appropriate
learning objects by their metadata, it is not clear whether it is possible for computer
agents to integrate these learning objects in an appropriate way to form a higher level of
course unit that makes instructional sense. Most e-Learning specification initiatives have
not mentioned this issue or just leave it to specification adopters to make the decision by
themselves. Thirdly, there are many e-Learning specifications in XML available now,
however each of them has its own emphasis, and none of them provides a complete
solution for developing an e-Learning system. Therefore, most online instructional
systems are still developed in proprietary ways without adopting the existing
specifications. Finally, although XML was introduced several years ago, it is far from
mature. Many technologies associated with it are still under development or change
frequently, and therefore learning specifications based on XML have to change
accordingly. Moreover, XML is difficult to work with, needing a careful design by
organizations that want to adopt it. All of these issues make the use of XML in
developing a reusable e-Learning system difficult to implement.
This thesis addresses the possibility of developing learning content based on learning
objects and the role played by XML for designing an e-Learning system. The main goal
of this research is to design a reusable and adaptive e-Learning system with XML
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schemas forming the basic framework. To implement this goal, the concept of a learning
object is redefined, and a schema for learning objects is developed. Some modifications to
the existing e-Learning specifications, such as the metadata specification, the content
packaging specification, and the learner information specification, are introduced to make
them more suitable for our e-Learning systems. In this thesis, four online tutorial courses
are developed to illustrate how these schemas can work together to make it possible to
reuse learning objects in different learning contexts and to provide learners with
individually tailored learning content.
Chapter 2 of this thesis provides background information on e-Learning. First, e-Learning
and the requirements of future e-Learning systems are reviewed. The concept of a
learning object is selected for a deep examination, since learning objects form the basic
foundation of an e-Learning system. Then the present state of XML, and issues such as
why XML should be used, and what are the benefits are discussed. Finally, the emerging
international standards for e-Learning systems are reviewed, along with the benefits of
open standardization.
In Chapter 3, the features of learning objects according to the new definition are
summarized. The schemas for learning object, metadata, content packaging, and learner
information are defined and explained.
Chapter 4 describes the architecture and detailed design of the experimental e-Learning
system, and Chapter 5 describes the implementation of this system. Chapter 6 summarizes
the thesis work, and discusses research contribution and future work related to the e-
Learning system.
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Chapter 2
Background
2.1 E-Learning, A New Way Of Learning
Education has evolved considerably because of Web technology. The Internet enables the
ordinary person to have access to never-ending quantities of information and knowledge
more efficiently and conveniently. The growth of the World Wide Web, high-capacity
corporate networks, high-speed desktop computers and all kinds of mobile devices will
make learning available to people 24 hours a day, seven days a week around the globe.
Since many traditional education organizations are using Web technology to deliver
educational content, it is possible now for a high school student to seek assistance with
mathematics questions at any time of the day or a graduate student at home to take some
courses through long distance education.
Web-based learning not only improves the achievement of students from kindergarten to
university, but also enhances the productivity of the corporate workforce. Turbulent
corporate environments, caused by market dynamics, have made knowledge and skills
indispensable for effective performance in the workplace. Knowledge in the workplace is
no longer implied but required at different times and different quantities. Traditionally,
corporate training has existed in organisations to impart knowledge to individual workers
as off-the shelf learning packages. In this model, learning takes a reactive approach to
problem solving encountered by organisations, and learning programs take place in a
specific location. However, recent advances in the fields of distributed and ubiquitous
computing, artificial intelligence, cognitive learning theory, and multimedia have
converged to provide more distributed learning systems over the Internet and World Wide
Web (WWW).
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A requirement for knowledge and skills distribution across different systems, space, and
time is pertinent to unique learning requirements of individual learners within all kinds of
organisations. The infrastructure to support such knowledge distribution is in the form of
electronic learning, normally referred to as e-Learning.
Commonly, e-Learning is defined as Internet-enabled learning, or convergence of
learning and the Internet, including any use of computers and the Internet to facilitate
education [Downs 1998]. The components of e-Learning can include content delivery in
multiple formats through the Internet, management of the learning experience, and a
networked community of learners, content developers and experts.
E-Learning covers a wide set of applications and processes such as Web-based learning
systems, computer-based learning systems, virtual classrooms, and digital collaborative
learning GroupWare packages. E-Learning content is mainly delivered via Internet,
intranet/extranet (LAN/WAN), audio- and videotape; satellite broadcast, interactive TV,
DVD and CD-ROM, and the still to emerge wireless application protocols (WAP)
[ASTD, 2001].
It is estimated that the e-Learning market will grow substantially over the next five years.
Moreover, with the improvement of bandwidth, video, and storage technology, the
demand for e-Learning products and service will increase exponentially [Wiley 2001].
2.1.1 The Features of E-Learning
E-Learning has the potential to revolutionize traditional education, because it could
provide faster learning at reduced costs, increased access to learning, and clear
accountability for all participants in the learning process. It enables businesses or schools
to distribute training and critical information to multiple locations easily. Employees and
students can then access training when it is convenient for them, at home or in the office.
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In today's fast-paced culture, organizations that implement e-Learning will provide their
work force with the ability to turn change into an advantage.
However, e-Learning is just now in its infancy [Downes 1998]. As pioneers struggle with
new technologies and new practices, the discipline evolves almost daily. Despite the rapid
change, some significant features of future e-Learning can be identified as the following:
Personalization. The education of the future will become deeply personalized.
The learning topics will be selected based on student interest, student aptitude and
educational level, and societal need. The menu of available courses presented to
any given student will be determined dynamically by the student's prior learning
assessment, by the prerequisite for the new course, and by the learning
management system. A student's daily menu will be varied and constantly
changing, building on each day's achievement.
Interoperability and reusability. E-Learning systems with different
environments and contents from multiple authors must have the ability to work
together. There must be a semantic relationship between different e-Learning
systems. Learning content may be reused in multiple applications andenvironments regardless of the tools used to create them. This requires that
content be separated from context-specific runtime constraints so that it can be
incorporated into other applications. For reuse to be possible, content must also
have common interfaces and data.
Flexibility. Courses could be generated in a variety of forms based on standard
style sheets. Different forms of layout could be available depending on the
purpose of the course and the preferences of the learner. A student can use various
kinds of devices with different processor speeds and memory capacity, from
desktop computers, laptop computers, and mobile devices such as Palm
computers, to access the learning content.
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2.1.2 A New Approach to E-Learning Content Development
Despite the wide spread use of e-Learning infrastructure in corporate and educational
environments, current approaches to the development of e-Learning content are expensive
and time consuming. It is common that content developed by a single vendor or
educational institution can be difficult to reuse by a second vendor or institution, even
though the content shares the same meaning and quality [Downes, 2001]. Failure of
systems to interoperate or exchange content and differences in content ontology between
institutions make content reusability and sharing difficult, although content sharing and
reusability will reasonably reduce production cost.
In order to make e-Learning content less expensive to produce and portable across
different hardware and software systems, a new way of developing e-Learning content has
been proposed. This new approach assumes that e-Learning content can be organised and
disseminated in a uniform format as small chunks of learning materials commonly
referred to as learning objects or knowledge objects [Clayton 2000] [Feemster 2000]. It
seems that developing and delivering learning content as objects will promote reusability,
interoperability and content sharing between different training vendors and educational
institutions. When combined, the learning objects, due to their reusability in different
learning scenarios may form educational resources that can be used in different
environments by different individuals. This realization leads many course developers to
believe that the learning object can become the foundation of adaptive instructional
systems that deliver individually tailored learning materials to large number of people at
the same time.
With standards and compliance in place, it is possible for learning materials to be reused
and to travel on different systems. However, another problem comes up due to
unstructured nature of most of the information available: how can someone search
through a vast online repository of objects to enable them to get what they need? The
answer is that learning objects must be associated with appropriate metadata. They must
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be labelled as to what they contain, what they teach and what technical requirements are
needed for their use. It should be also noted that issues of content relevance, systems
compliance, and the nature and structure of content are important problems to solve when
designing reusable e-Learning content. Currently, the main technology used for tagging
learning objects is the eXtensible Makeup Language (XML) [Fox 2000] [Gerber 2001].
2.2 Learning objects
2.2.1 Background Literature on Learning Objects
The complexity and contradictions about what constitutes a learning object are reflected
in the different views expressed in its definition. The IEEE Learning Technology
Standards Committee (LTSC) describes learning objects as any entity, digital or non-
digital, which can be used, re-used or referenced during technology supported learning
[LTSC 2002]. It goes on to argue that learning objects include multimedia content,
instructional content, learning objectives, instructional software and software tools, and
persons, organizations, or events referenced during technology supported learning.
However, this definition is so broad that anything related to learning can be interpreted as
a learning object. Therefore, several groups outside the LTSC have accordingly created
some new definitions of learning objects, which normally narrow the scope to something
more specific. Following are some definitions that have been adopted by various
organizations and companies:
[IDC 2001] white paper asserts that a learning object is a standalone piece or
chunk of education that contains content and assessment based on specific
learning objectives and that has descriptive metadata wrapped around it.
[Shepherd 2001] defines a learning object as a small, reusable digital component,
which can be selectively applied - alone, or in combination - by computer
software, learning facilitators or learners themselves, to meet individual needs for
learning or performance support.
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[Wiley 2001] concludes a learning object is any digital resource that can be used
to support learning. He claims that this definition is sufficiently narrow to define a
reasonable scope: reusable digital resource, and is also broad enough to include
the estimated 15 terabytes of information available on the publicly accessible
Internet.
Given all these definitions, there still seems to be little clarity, specifically on what forms
a learning object. However, important features of learning objects, shared by most of the
definitions, are centred on the grounds that the use of learning objects should be focusing
on reusability and sharing.
Those definitions explicitly rule out any non-digital and non-reusable resources, such as
actual people, events, books, or other physical objects. Examples of learning objects
includes the smaller digital resources, such as images, paragraphs of text, questions,
animation, audio or video clips, and also the larger resources, such as entire web pages
that combine text, images and other media applications to deliver complete instruction.
These objects, which are reusable, should be stored in repositories and the copies of their
metadata should be available in computers easily accessible by users [Downes 2001];[Shata 2001].
The idea shared by these definitions is that by building learning resources as reusable
learning objects, developers of learning materials, learning managers and learners
themselves will all stand to gain [Klassen 2000]. The benefits can be summarized as the
follows:
Courses can be constructed using learning objects from a wide range of resources.
Course developers do not need to prepare all course materials from scratch,
therefore they can produce courses more economically;
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Courses can be customized to suit the needs of different learners by selecting
different learning objects according to the requirement and the interest of learners;
Learning objects can be reused to meet a range of learning needs. It is not
necessary to develop similar learning objects for multiple times;
The same objects can be employed across a variety of hardware and software
platforms, when common standards are followed by the learning objects.
2.2.2 Reusability of Learning Objects
Reuse has existed in the field of software engineering for decades. Software reuse is the
process of creating software systems from predefined software components [McClure,
1995]. The greatest benefit of reuse arises from the possibility for rapidly assembling
small components into complex ones.
With object-oriented design and programming, a completely new way of thinking about
the construction of complex systems was originated. Object orientation allows software
components to be used as building blocks for future software developments and takes
components created by others rather than creating new ones from scratch. In this sense,
learning objects are an application of object-oriented design to the world of learning.
Reusable learning objects represent an alternative approach to content development.
Learning objects treated as small components are pedagogically broken down into small
chunks. Better yet, from a pedagogical perspective, each chunk plays a specific role
within an instructional design methodology. The basic requirement for each chunk is its
ability to communicate with any learning systems using a standardised method that does
not depend on a specific system. Akin to the behaviour of small software objects in the
object-oriented programming model, what happens within an individual learning object is
trivial, since this is obscured from the designer and the user.
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Each learning object must have a description that enables designers and computer agents
to search for and find the right objects for the right job. This implies that objects must be
wrapped in metadata. Whatever the properties the learning object has, the metadata itself
should be straightforward. Moreover, since the metadata is machine-readable, it must be
possible for a specific system to interpret the metadata from other sources and then reuse
the learning objects. However, it should also be noted that metadata is limited because it
is only a wrapper for the search engine to identify one object from another. The
knowledge bits inside a learning object cannot be distinguished by metadata.
2.2.3 Problems with Learning Objects
Although it is a good idea to develop course content based on learning objects, some
problems still exist. The learning objects are designed not only for direct human
processing but also for automatic machine processing. They should allow processing by
intelligent services such as information brokers and search agents, which provide greater
functionality. For example, one important benefit that these reusable learning objects can
offer is that, by mixing and matching them, an e-Learning system may customize learning
for individuals. It is also described in the proposal of the Learning Objects Metadata
Working Group formed by LTSC, which tries to enable computer agents to
automatically and dynamically compose personalized lessons for an individual learner
[LTSC 2002]. However, several questions will be raised when we design an e-Learning
system to fulfill this goal:
How should we define the level of granularity of learning objects? Does it make
sense to view any single image, paragraph of text or a question as a learning
object?
Is it possible to use search agents to select and integrate the learning objects in an
appropriate way to form a higher level of course unit, which make instructional
sense?
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Are metadata sufficient to facilitate the combination of learning objects?
The important issue not clearly addressed in the literature on learning objects is the
granularity and combination of learning objects. Granularity refers to the size of the
learning object and combination refers to the manner in which learning objects can be
combined and assembled into larger structures to enhance learning [Wiley 2000] [Jamlan
2001].
For two extreme examples, a learning object can be as small as a piece of an image or as
large as a complete course. For the former, such a learning object may be reused by a lot
of courses, however it is difficult, if not impossible, to select those individual learning
objects and combine them directly by computer agents in a way that makes instructional
sense. For the latter, although one can easily re-sequence a complete course in a new
context, the potential reusability of this learning object will be low.
[TechLearn 2001] has reported that there are no clear standards for the size (or
granularity)of a learning object. However, studies show that larger learning objects are
typically harder to reuse than smaller ones [Daniel, 2001]. From an efficiency point of
view, the decision regarding the granularity of learning objects can be viewed as a trade-off between the possible benefits of reuse and expense of combination.
Granularity and combination issues in the design of learning objects are tantamount to
issues of scope and sequencing of learning materials in instructional design [Wiley, et. al,
2000]. The way in which learning objects can be combined with other learning objects is
very much dependent on their scope and structure. However, traditional instructional
design theories that provide explicit scope and sequencing support are not applicable to
learning objects. [Wiley 2000] further argues that the structure of learning and the
combination of objects are like molecular bonding process; molecules of the same nature
can be combined to form complex structures.
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Currently a clear ontology for defining learning objects is lacking. Furthermore, if
learning objects are solid entities, which can be referenced by others, as proposed by the
principles of object orientation, then a learning object should support some kind of data
structure.
To address those problems, [Daniel 2001] has initiated a new attempt to characterize
learning objects as pieces of instruction but not just pieces of digital information. He
claims that a learning object should provide instruction on a relatively small, discrete skill
or unit of knowledge, and the content of a learning object should be self-sufficient,
independent of the context. Even so, it should be possible for a learning object to be used
in more than one sequence of instruction.
In this proposal, we will further discuss the features of learning objects in chapter 3,
where we redefine the concept and develop a schema for a learning object.
2.3 E-Learning and XML
For all the new features and technical demands of future e-Learning, XML seems to be a
reasonable answer [Adolphe 2000]. XML is an important step in the direction ofpromoting the interoperability and flexibility of Internet applications. As a simplified
subset of SGML, XML was created as a way to structure, store and send information on
the Internet. Unlike HTML, XML allows someone to create his/her own tags and define
the DTD (Document Type Definition) or XML Schema. The DTD or schema supports a
tree structure, which is much richer than a simple flat list and also respectful of cognitive
and data processing requirements for economy and simplicity.
When XML is used to store unstructured or semi-structured data, for which the traditional
relational database is not suitable, it gives developers the ability to manipulate the
information easily and quickly. With XML, course developers may put semi-structured
information, such as the course content or course structure, into a discrete relational field,
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and then work with this information as with structured blocks of data, not as with a string
of bytes.
Therefore, for e-Learning XML provides a flexible approach to represent the content and
the structure of a course, and to keep such information separate from the software used for
delivery and presentation. Moreover, content stored using XML can be independent of
any course, and is in a form ideally suited to re-use in any number of different courseware
and other learning-related products. For example, learning content in XML may be
transformed into PDF to form a part of a book, or into HTML to provide online education.
With the current intense interest in XML and rapid progress in the area of XML data
management, more and more attention has been paid to using XML as an intermediate
format for Web-based information representation, exchange, retrieval and reasoning
[Nauer et al.2000]. It is widely acknowledged that XML will form the standard for data
interchange in electronic commerce, and that the management of large and complex web
site will be much improved by the use of XML.
As the e-learning market grows dramatically, an increasing number of organizations and
vendors are using XML as a standard way to tag or mark up learning information, such as
learning materials, management resources, and student data, so that they can be easily
referenced, read, and exchanged across applications and systems. [Gerber 2001] points
out that XML allows e-Learning designers and administrators to develop applications
faster, reuse course content easily, and facilitate data exchange between Web-Based
courseware content and learning management systems.
However, XML is not a single specification. A rich environment surrounding XML has
been developed by the World Wide Web Consortium (W3C) and others since 1998. This
environment includes many important specifications, such as DTD, XML Schema,
Namespaces in XML (XML Names), Xpath Language (Xpath), Extensible Stylesheet
Language (XSL), XSL Transformation (XSLT), XML Query, XML Document Object
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Model (DOM), XML Linking Language (XLINK) and XML Pointer Language
(Xpointer), many of which can be used in an e-Learning system.
2.3.1 XML Schema and its Benefits for Interoperability and Reusability of
Information
In online systems, the most popular use for XML is to create a separation of content and
presentation [Box et al. 2000]. In this situation, we are defining application content as the
data that needs to be displayed to a client or processed by a computer agent, and
application presentation as the formatting of that data. XML is a markup language for
documents containing semi-structured information. Information is stored in XML
documents with a logical structure, therefore it is meaningful and machine-processible.
This kind of format improves the interoperability and reusability of information, and
makes flexible Web-based information representation, exchange and retrieval possible.
Both a DTD and an XML Schema can be used to define the tree structure and establish a
set of constraints for an XML document. However, DTDs have no formal mechanism to
support the declaration of semantic integrity constraints. They show some critical
limitations: DTDs are not themselves XML documents; they have no knowledge of
hierarchy, they have difficulty in handling namespace conflicts, and they have no means
of specifying the types of relationships allowed in XML documents.
For these reasons, the XML Schema specification was developed to replace and amplify
DTDs. Schemas express shared vocabularies and allow machines to carry out rules made
by people. They provide a means for defining the structure, content and semantics of
XML documents. XML Schemas have the same purpose as DTDs, but provide several
significant improvements [Fallside 2000]:
XML Schema definitions are themselves XML documents;
XML Schemas provide a rich set of datatypes that can be used to define the values
of elementary tags;
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XML Schemas provide a richer means for defining nested tags (i.e., tags with
subtags);
XML Schemas provide the namespace mechanism to combine XML documents
with heterogeneous vocabulary.
These new features are important progress in the development of XML. They will
influence the ways in which XML can be used. XML Schemas offer an XML-centric
means to constrain XML documents, or to bring DTDs back into line with XML itself.
Every tool that handles an XML document can also be used to deal with schemas.
XML Schemas provide a rich set of datatypes and a richer means for defining nested tags.
This makes XML languages more like an object-oriented programming language such as
Java. Like the definition of data structures of objects in Java, schemas define and model
complex object semantics for XML documents, where semantics fundamentally means
an intricate web of constrained relationship and properties [Cover 2000].
XML Schemas supports a flexible way to use namespaces. Namespaces are the mappings
used for handling definition collisions, when several data type definitions are adopted by
the same XML documents. Namespaces were invented after DTDs and are not fullysupported by them. However, XML Schemas provide a more advanced namespace
mechanism to combine XML documents with a heterogeneous vocabulary. A customized
XML Schema would allow an XML document to make a reference to standard schemas
whenever necessary. This method could improve the interoperability of XML documents.
On the Internet, interoperable exchange and retrieval imply the existence of a sharable
ontology, or common set of object semantics [Klein et al. 2000]. XML Schemas fulfill a
major goal in common with ontology, namely providing semantic vocabulary and
structure for describing information sources that are aimed at data exchange and
information retrieval. Using XML in building learning objects and other learning
information enables designers to share content with their colleagues or with course
designers in other organizations. It should be noted that if a common schema is developed
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and adopted, information tagged in XML for one system could easily be integrated with
any other system.
For instance, using XML as a language of metadata allows the user to create new kinds of
descriptors that feature the learning objects. Since the schema ensures that the metadata is
machine-readable and meaningful for the search engines, any learning management
system (LMS), which chooses to support this schema, can use this metadata to select
learning objects. Furthermore, through the use of XML Schema, learning objects can be
structured and presented as nodes of trees in a content packaging file to reflect different
levels of learning granularity and seqencing, which makes the combination of learning
objects possible.
2.3.2 XSL, XSLT and XPath for Flexible Information Presentation
XSL is the Extensible Stylesheet Language. XSL transforms and translates XML data
from one XML format into another. XML provides a way to store data with logical
structures and to define a semantic constraint on the data, but it does not tell how to
present the data. In order to display XML documents to the clients, it is necessary to have
a mechanism to describe how the document should be displayed. One of these
mechanisms is Cascading Style Sheet (CSS), but XSL is the preferred style sheet
language for XML, and XSL is far more sophisticated than the CSS used by HTML.
XSL actually consists of three languages [Berlund et al. 2000]:
XSLT is a language for transforming XML documents into other types of
documents, or into other XML documents.
XPath is a language for addressing parts of an XML document. XPath was
designed to be used by XSLT.
XSL Formatting Objects is an XML vocabulary for specifying formatting
semantics.
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XSL is a powerful style sheet for XML documents. Instead of having to rewrite the course
content in different formats or in a different length, the developers can use XML to
separate content from the way it is presented. That allows them to re-organize the content
and make tailored courses for a specific learner in an appropriate format. For example, the
same XML document may need to be displayed in HTML, PDF, and Postscript form.
Without XSL, the XML document would have to be manually duplicated, and then
converted into each of these three formats. Instead, XSL provides a mechanism for
defining stylesheets to accomplish these types of tasks. Through some standard XSL files,
an XML file can be transformed into different formats without having to change the data
due to the requirement for different representations. In this way, XSL helps XML fulfill
reusability of content.
For mobile devices that want to access the learning content, Wireless Markup Language
(not HTML) is used. WML is defined as an XML 1.0 application, so XSLT can also be
used to transform the XML documents to WML files, and then the Palm computer or
mobile phone displays the WML files. With XSL, XML will implement a flexible
information presentation with little effort.
2.3.3 XML DOM and SAX
The personalization of learning content means that every learner may get information
matching particular requirements. Therefore, it is necessary to search and retrieve
different information from the XML documents for different learners. As a data-driven
markup language, XML can be easily searched and manipulated due to the strict structure
and semantic constraint that schemas can impose [Boyle 2000].
XML is simple and easy to use, since there are some software packages for XML parsing.
Right now, two APIs for XML, SAX (Simple API for XML) and DOM (Document
Object Model) are normally adopted. With the SAX, developers have access to the
information in XML documents as they are read, without imposing major memory
constraints or a large code footprint. Meanwhile, DOM is designed to generate a
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representation of an XML document as a tree, therefore users may traverse and
manipulate the tree structure to retrieve the data.
As W3C specifications, both DOM and SAX provide a standard programming interface to
a wide variety of applications for XML. They are designed to be used with any
programming language and any operating system. With DOM and SAX, a user can create
an XML document, navigate its structure, and extract, add, modify, or delete its elements.
Several tools currently used these APIs and provide the means to parse a XML document.
2.3.4 Conclusions about using XML
From the above review of XML and the technologies associated with it, it is clear that
XML can benefit an e-Learning system with several advances. Firstly, XML Schemas
provide a way to define a set of elements, which can establish a shared ontology among
different organizations. This helps learning materials go through platforms and be reused
without the problem of compatibility. Secondly, the separation of content and
presentation will enhance the flexibility of displaying learning materials. By adopting the
standard XSLT files, learning materials may be transformed into a variety of possible
standard forms. Lastly, information stored in XML files is easy to search and retrieve due
to the structure and constraint that XML files followed.
It seems that XML is almost ready to be used in such online systems as e-Learning.
However, it should be noted that change and development is occurring rapidly, and that
XML is far from stable. Some guides about using XML in e-Learning system have been
published, however, no practice and experimental data are available yet. Therefore, using
XML in a realistic environment is just in a tentative phase now.
2.4 E-Learning Standards
Why should we develop standards for e-Learning? Maybe we can get some inspiration
from the Lego system, the childrens construction toy. Although individual Lego pieces
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have different shapes and sizes, they always follow the standard units of measurement and
standard interfaces. Therefore, no matter how one wants to reassemble the pieces, they
always fit together. The idea behind standards for e-learning is exactly the same. If the
learning objects and metadata follow common standards, the course developers or
computer agents can eventually form an integrated course by assembling all kinds of
learning objects.
In the e-Learning community, XML forms the basic foundation for inter-application
communication, however it does not ensure that communication will happen. For
example, people speaking different languages cannot understand each other. Even in the
same language, such as English, words may have different meanings; the word football
represents different sports in England and North America. To make communication
possible, a set of vocabularies with clear definitions should be shared by speakers. That is
what some organizations are doing; developing standards in XML for e-Learning. In this
section, we will survey some important organization and potential standards in e-Learning
community.
2.4.1 Standards Initiatives for E-Learning
Strictly speaking, there are just a few e-Learning standards now. Several organizations are
concerned with e-Learning specifications that the learning community may support.
Amongst them, Learning Technology Standards Committee (LTSC) from Institute of
Electrical and Electronic Engineers (IEEE), the Aviation Industry Computer-Based
Committee (AICC), the Instructional Management System (IMS), the Advanced
Distributed Learning (ADL) and the Educational Modelling Language (EML) are the
leading ones.
IEEE LTSC
IEEE, ISO (International Standards Organization) and ANSI (American National
Standards Institute) are the major organizations that set most official computer standards.
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IEEE has developed many technology standards for electrical and information
technologies and sciences. Several years ago, it set up the LTSC to develop technical
standards, recommended practices, and guides for software components, tools,
technologies and design methods that facilitate the development, deployment,
maintenance and interoperation of computer implementations of education and training
components and systems [LTSC 2002]. Currently, the committee is carefully reviewing
the specifications created by IMS, ADL and AICC, comparing and combining them, and
making sure that they are general enough to fit the requirements of any learning
organizations. Several working groups have been formed concerning the standards in a
number of areas, such as glossary, student identifiers, learner models, course sequencing,
content packaging, learning object metadata and so on. The standard for learning object
metadata was approved on June 13, 2002, by the Standards Board of the IEEE Standards
Association.
AICC
In 1988, AICC was first formed to propose hardware requirements for running computer-
based training (CBT) software developed for the aviation industry. However, it has since
branched into several other areas [AICC 2002]. In recent years, the AICC has developed
guidelines for the aviation industry in the development, delivery, and evaluation of CBT
and related training technologies. AICC recommendations are fairly general to most types
of computer-based training and, for this reason, are widely used outside of the aviation
training industry. It also actively coordinates its efforts with broader learning technology
standards organizations like IMS, ADL, and IEEE/LTSC.
IMS
IMS may be the most influential organization in the e-Learning community. The
contributing members of IMS include many well-known academic, corporate, non-profit
and government organizations. IMS is developing and promoting open specifications for
facilitating online distributed learning activities such as locating and using educational
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content, tracking learner progress, reporting learner performance, and exchanging student
records between administrative systems [IMS 2002].
Because XML has shown its advantage in the interoperability and reusability of data, IMS
adopts XML in all of its specifications. Now five specifications are available. When
designing our e-Learning system, we were aware of these specifications and tried to adopt
them in our system [IMS 2002]:
The IMS Learning Resources Meta-data Specifications creates a uniform way for
describing learning resources so that they can be more easily found [IMS 2000c].
The IMS Enterprise Specification deals with administrative applications and
services that need to share data about learners, courses, performance, etc., across
platforms, operating systems, user interfaces.
The IMS Content & Packaging Specification is concerned with creating reusable
content objects [IMS 2000a].
The IMS Question & Test Specification addresses the need to be able to share test
items and other assessment tools across different systems [IMS 2000d].
The IMS Learner Profiles Specification looks at ways to organize learner
information so that learning systems can be more responsive to the specific needsof each user [IMS 2000b].
ADL
The initiative of ADL is to accelerate large-scale development of dynamic and cost-
effective learning software and to stimulate an efficient market for these products in order
to meet the education and training needs of the military and the nation's workforce of the
future [ADL 2002]. It achieves this through the development of a common technical
framework for computer and net-based learning that will foster the creation of reusable
learning content as "instructional objects."
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ADL has developed the Sharable Courseware Object Reference Model (SCORM)
initiative. SCORM includes four major areas: metadata, course structure format, data
model, and an application program interface or API. To avoid reinventing the
specifications, SCORM integrates specifications from IMS, AICC and IEEE. It also
created a software program to test the learning objects, learning management system, and
course delivery tools for compatibility.
EML
EML is a research program for educational modelling carried out by the Open University
of the Netherlands (OUNL). It tries to develop a comprehensive notational system that
allows course developers to codify units of study (e.g. courses, course components and
study programmes), in an integral fashion. EML describes not just the content of a unit of
study (texts, tasks, tests, assignments) but also the roles, relations, interactions and
activities of students and teachers. The major EML implementation is in XML [EML
2002]. However, EML pays less attention to the possibility of reusing study units in
different course contexts. It mainly focuses on how the course structure should be
described and how an instruction course should be navigated during a learning process.
This limitation impairs its potential to become an e-Learning standard.
Amongst all of these specifications, the metadata and content packaging or course
structure specifications may be most important ones. In the following section, we will
discuss these two specifications.
2.4.2 Specifications for Metadata
Metadatais known as "structured data about data." The term metadata has been used only
in the past 15 years, and has become particularly common with the popularity of the
World Wide Web. The purpose of metadata is to provide a common way to describe
resources so that they can be self-defined and searched [Gerber 2001].
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The first organization dedicated to promoting the widespread adoption of interoperable
metadata standards is Dublin Core Metadata Initiative [DCMI 2002]. It developed a set of
simple specialized metadata vocabularies for describing resources that enable more
intelligent information discovery systems on the Internet. Nowadays, many web sites
adopt DCMI to describe their web pages.
However, in an e-Learning system, DCMI is too simple to support effective resource
discovery. It lacks the elements that may be used to describe the educational features of
learning objects. Therefore, a number of organizations, such as IMS, ADL, and LTSC
Learning Object Metadata (LOM) working group, are trying to develop a new metadata
standard for learning objects. Over the past few years, the IMS have defined a standard
dictionary of metadata elements, which is referenced and used by ADL. Some other
initiatives, such as Canadian Core Learning Resource Metadata Protocol (CanCore), also
follow this specification [Gerber 2001]. The LOM, which has been approved as an IEEE-
SA standard, is also built on IMS Metadata Specification [LTSC 2002].
IMS Metadata Specification
One of the key contributions of IMS is the IMS Learning Resource Meta-data
Specification, an XML-compliant schema for indexing learning objects [IMS 2000c].
The growing popularity of this schema among e-learning projects such as SCORM
(Sharable Content Object reference Model), and MERLOT (Multimedia Educational
Resource for Learning and Online Teaching) and its adoption by a number of educational
repository projects suggests that IMS will become the standard means of describing
electronic educational materials [Lin 2001].
There are 86 elements in total in IMS metadata, which make the metadata a little
complex. All the elements are divided into 9 categories, and each describes one kind of
feature about the learning object:
general Groups information describing learning object as a whole;
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lifeCycle History and current state of resource;
metaMetadata Features of the description rather than resource;
technical Technical features of the learning object;
educational Educational or pedagogical features of the learning object;
right Condition of use of the resource;
relation Features of the resource in relationship to other learning objects;
annotation Comment on the educational use of the learning object;
classification Description of the characteristic of the resource by entries of
classification.
CanCore
CanCore Protocol is based on and fully compatible with the IMS Learning Resource
Meta-data Information Model. CanCore has defined a sub-set of data elements from this
IMS model for the purposes of the efficient and uniform description of digital educational
resources in Canada and elsewhere [CanCore 2002]. It is intended to facilitate the
interchange of records describing educational resources and the discovery of these
resources both in Canada and beyond its borders. Currently, the CanCore schema
provides 54 elements in total, which is a little less than IMS specification.
2.4.3 Specification for Content Packaging or Course Structure Format
The learning objects and metadata often need to be collected and packaged to enable
efficient aggregation, management, and deployment. Therefore content packaging or
course structure format can be used as a top-level manifest file describing the course
elements, the course structure, and all external references necessary to represent a course
and its intended behaviour. There are two kind of content packaging used by e-Learning
systems, the Content Packaging conceptual model from IMS and the Course Structure
Format (CSF) from ADL. The IMS content packaging is simpler and clearer than CSF,
and allows references to CSF to be made by using a namespace [Shata 2001]. However,
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none of them can provide an efficient way to describe the hierarchical structure of an
instructional course, which contains course design information.
IMS Content Packaging Specification
The IMS content packaging conceptual model creates a Package Interchange File which is
a single file, e.g. zip, jar or cab which includes a top level manifest file describing the
package as a whole[IMS 2000a]. A package represents a unit of usable content, which
includes all learning materials and the associated metadata. A content packaging file is
used to describe in XML all the resources comprising a package and one or more ways of
organizing the resources for presentation.
Figure 2.1 Content Packaging
As described in [IMS 2000a], all data in this e-Learning system could be organized as
Figure 2.1 depicts. The root element in the content packaging file is , which
may also contain optional (sub)manifests. Each instance of a manifest consists of two
major parts: the element describes the content organization and the
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element contains all references to all the actual resources. The organization
of the manifest and its nesting functionality permit a great deal of flexibility, which
allows developers to aggregate or disaggregate their material as they wish, thus a package
might be a unit in a course, a whole course or a whole curriculum of courses. The actual
resources form part of the package, with suitable metadata describing each resource.
2.4.4 Specifications for Question & Test Interoperability Specification
The IMS Question & Test Interoperability Specification provides proposed standard XML
language for describing questions and tests. The specification has been produced to allow
the interoperability of content within assessment systems [IMS 2000d]. It describes a
basic structure for the representation of question (item) and test (assessment) data and
their corresponding results reports. Therefore, the specification enables the exchange of
this test, assessment and results data between Learning Management Systems, as well as
content authors and, content libraries and collections.
2.5 Summary
In this chapter, we have reviewed a new approach to education, e-Leaning, and some
important topics around it, such as leaning objects, XML and open standards. It should be
noted that the key problems with learning objects, namely granularity and combination,
are still unsolved. Moreover, the use of XML is still not universal in the e-Learning
community and XML is not used in a consistent manner. There is no specification for
learning objects and the content packaging specification provides no information about
instructional design. Those problems make it difficult to develop an e-Learning system
based on XML that accomplishes reusability, interoperability and flexibility.
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Chapter 3
Schema Design
Before designing an e-Learning system based on XML, some fundamental concepts and
ideas must be clarified. For course designers, the idea of learning objects requires an
immense change in thinking. Instead of looking at learning as a fixed linear progression,
we must now look at learning as clusters of independent, stand-alone objects ofknowledge. These learning objects should be dynamically selected and sequenced by
computer agents to form an individually tailored course.
The key problem here is how we should handle these learning objects. We need to find a
way to ensure that these objects can be more easily accessed, can be located by computer,
can be easily updated, and can be seamlessly tied in with other objects to make a more
complete learning package. We also need to make sure that the learning course built on
learning objects can present clear objectives, integrated content, and carefully sequenced
instructional activities.
One answer for this is to use XML as metadata for describing the learning objects. In an
e-Learning system, we use metadata to support resource discovery. Every learning object
will have associated metadata that is written in XML and conforms to a particular XML
Schema. The schema gives specific constraints on the structure of metadata, and also
provides information about the interpretation of the metadata. A series of tags defined in
the schema are combined together to describe the learning objects. A designer or a search
engine will look at the metadata to decide how to find the necessary learning objects and
reconstruct them again.
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However, metadata alone is not enough. To make it possible for computers to make
sequencing or any other instructional design decisions, the computers must have access to
instructional design information to support the decision-making process. Therefore, it is
necessary to have some way to describe the organizational structure of the learning
objects and to include enough instructional design and sequencing information. Moreover,
to make the instructional design suitable for an individual user, background information
about learners is also required.
Therefore, a basic framework for an e-Learning system becomes clear. A library of
learning objects with metadata forms the basis of the system. In order to construct
personalized courses for learners, a data model of a learner is needed to provide
background information to describe the learners needs. The Learning Management
System, including a search engine, uses the learners interests to select appropriate
learning objects and then pieces together courses based on the organizational structure
and instructional design information
In our project, the following aspects are defined in XML schema:
The learning object; Metadata for retrieval and reuse;
Content packaging for the learning structure, including information about
sequences and alternations of the learning objects;
Learner model, including the learners personal properties, such as skills, prior
knowledge, and background information.
Since schema development is an expensive process, in this project, we borrow from
existing standards or specifications when possible, such as the metadata specification, the
content packaging specification and the learner information specification. However, it
should be noted that some modifications are needed to make the schemas more suitable
for a reusable and adaptive e-Learning system. Moreover, we redefine the concept of
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learning object and develop a schema for it according to the new features that we have
summarized.
All of these four schemas and a learning management system form the foundation of the
whole e-Learning system. In the following section, the schemas are described in detail,
and the instance XML documents conforming to the schemas are provided in Chapter 4.
3.1 Schema for Learning Objects
3.1.1 New Definition of Learning Objects
As mentioned above, if we define learning object in too broad a way, we lose any useful
meaning about learning object. Although reuse is the core of the learning object notion, as
flexibility, adaptivity, and interoperability are all facilitated by the property of reuse, there
is still a trade-off between the benefit of reuse and the cost of combination and re-
sequencing. In this research, we prefer a much narrower definition, which makes the
automatic construction of individually tailored courses possible.
According to a common definition, a learning object is a small, reusable digitalcomponent that can be selectively applied - alone or in combination to support learning.
This definition makes it impossible to develop a schema for learning object, since any
digital resource, such as a single picture or a whole web site, can be viewed as learning
objects. It is difficult to find a common structure among those resources and to define the
granularity of learning objects. However, to travel across different platforms, learning
objects should have a uniform format. Moreover, such a format should be able to facilitate
the reuse and re-sequencing of learning objects. Therefore, we need a more specific
definition.
In our research, a learning object is defined as a combination of smaller knowledge bits,
such as text, image, and audio or video clips, which are integrated together to explain or
describe a single core concept in a course. Each learning object can stand alone as a
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collection of content items, practice items and assessment items that are combined based
on a single learning objective. The critical features of a learning object may be
summarized as follows:
A learning object is an integrated knowledge object, focusing on a core concept, not just
a piece or a chunk of information.
Normally, a learning object is smaller than a course, a module, or a lesson. However, in
order to describe or explain a single core concept clearly, a learning object may still
include some integrated knowledge bits, which may be in different formats, such as text,
pictures, video clips, maps or simulations. All materials in a learning object will be
organized to surround and describe a core concept. It is likely that the organization of a
learning object should include a definition of the core concept, detailed description of the
concept and sometimes several examples, a conclusion, and some test items or exercises.
When a single text, image, video clip or a combination of those materials cannot provide
a comprehensive instruction independently and needs be joined with other materials to
explain a core concept, it will not be viewed as a learning object.
A learning object cannot include a complex hierarchical structure.
Learning objects are the lowest level of curriculum structure; therefore unlike the upper
level structures of a course, such as lessons, modules, units or topics, they cannot have
embedded concepts or units. Normally, a learning object should just have a flat structure.
The constituent parts in one learning object are all in identical status. It is prohibited that a
description about the core concept also contains another definition and description about a
new concept. This means that if a learning content for one concept is constructed by
several smaller sub-concepts, and each of the sub-concepts can form a stand-alone
content, the instructional content about this concept may not be developed as a learning
object. Instead, several smaller learning objects should be established to describe the sub-
concepts, which are then assembled and combined to instruct a more complex concept.
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A learning object is the basic reusable unit.
The greatest potential for reuse exists when the learning object centres on a single, core
concept and does not rely on the support of other course contents or context to clearly
provide instruction on this concept. A learning object can be used in more than one
sequence of instruction. For example, when designing the hierarchical structure of a new
course, the designers can just indicate what kind of learning objects are necessary, and
then the search engine may find the appropriate learning objects from the global
repository of learning objects. However, the knowledge bits in a learning object are not
necessarily reusable units which can be handled directly by a search engine. If the
designers only want to reuse some parts of the knowledge bits in a learning object, they
should inherit this learning object or construct a new learning object by using some
knowledge bits in this learning object. However, in such case, the work must be done by
the instruction expert, not by a search engine.
Several learning objects may describe the same concept.
Since the users of a course may have different backgrounds, studying abilities and diverse
levels of interests, for one specific concept, a learning system should provide different
learning objects that may range from easy to difficult or from simple to complex.
However, the learning objects that describe the same concept will probably have some
common parts. To avoid multiple duplications of the content, some disciplines in object-
oriented programming may be adopted, such as inheritance. Therefore, from one basic
learning object, a set of extended stand-alone learning objects can be developed, which
may be more difficult or more comprehensive. In such a case, a schema can be used to
keep a consistent structure, which enhances inheritance between learning objects
A learning object often includes some test items to evaluate the learners performance.
To make learning objects independent of course context and reusable in different course
sequences, learning objects should include the test items by themselves. Directly tied to
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the core concept, test items may be used to identify whether a learner has mastered a
given learning object. With test items a learning object will not solely depend on the high-
level context to evaluate the learners performance, and therefore fulfils a special learning
objective on its own.
A learning object must be searchable.
Each learning object should be associated with metadata. The attached metadata can
implement the express goal of interoperability, which allows search engines throughout
the world to be able to successfully find and use learning objects.
A learning object will normally be embedded in a hierarchical structure.
Each learning object provides stand-alone instruction, so it is difficult to define the
connection between learning objects in the content of a learning object itself. To help the
learner comprehend the whole structure of a course or smooth the flow in the instruction,
a hierarchical structure about the instructional content is necessary, which is used to
connect learning objects.
The preferred form of representation of learning objects is XML.
Learning objects in the form of text can be directly represented in XML. The XML tags
make the data in the learning objects meaningful, so the components in the learning
objects can be searched, extracted and reused in various ways. In addition, learning
objects in XML can be transformed to a variety of forms, such as PDF or WML, based on
standard style sheets. This makes the whole system more flexible.
In general, the granularity and combination of learning materials are implemented at two
levels. At the low level, the learning object combines several knowledge bits to explain a
concept, and at the higher level, the hierarchical structure describes the aggregation of
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learning objects to form courses. This constitutes the solid underpinnings of a schema for
learning objects.
3.1.2 The Design of a Schema for Learning Object
In this project, we define a Learning Object Mark-up Language (LOML), which is an
XML-based markup language designed for instructional contents. Because our specific
interest is in the domain of Computer Science, this language is applied specially to
describe topics as they apply to the field of Computer Science. When designing this mark-
up language, we have taken into account the critical features to choose a simple set of
mark-up tags to define the structure of a learning object.
Diagram
Attribute Name Type Use
inheritance xs:anyURI optional
Figure 3.1: Structure of Element
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Figure 3.1 shows the first level of elements of LOML. In this thesis, all diagrams for the
schemas are generated automatically by XML Spy, so they will follow the same style.
The notations in this diagram are mainly adopted from UML (Unified Modelling
Language) with some revisions. Each rectangle in the diagrams represents an element,
with the name of the element inside the rectangle. If two rectangles lap together, it means
that this element may appear multiple times. The signal + at the right side of the
rectangle indicates that this element has also some sub-elements, which are not shown in
the diagram. The switch notation between the root element and the
first level elements means that one may choose any element from the first level element in
any order to occur in an instance XML document. However, if the notation is a straight
line, this means that the elements may just appear in the sequence that has been defined.
In this schema for learning objects, the root element is . Other elements
are organized into eight different categories:
title The title of the learning object;
definition The definition of the core concept on which the learning object
focuses;
description Some detailed descriptions of the core concept;
exampleSome examples about the core concept; application Simulation or demonstration used to explain the core concept;
conclusion The conclusion about the core concept.
exercise The exercise used to improve the study of learner.
test The test used to evaluate the result of study.
The inheritance attribute of the root element indicates from which learning object the
current learning object inherits instructional content. If the attribute is not empty, the
XML file indicated by the attribute will be loaded and combined with the tagged contents
in the current learning object to form a complete description of the core concept.
For each sub-elements of the root element, a unique id is assigned, which can be used as a
reference to this element. Each element may also have reference attribute and status
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attribute. If the learning object inherits content from a parent learning object, the
reference attribute indicates one specific element in the parent, and the status attribute
indicates what kind of action will be taken. The following lists the available actions:
If the status is substitution, it means that the content in the current element
should replace the content in the parent element, which is indicated by the
reference attribute;
If the status is integration, it means that the content in the current element
should integrate with the content in the parent element, and then combine together
to form a single content;
If the status is connection, it means that the current element and its content
should be inserted behind the parent element;
Diagram
Attribute Name Type Use Facetsid xs:string required
reference xs:string optional
status statusType optional substitution, integration, connection
Figure 3.2: Structure of Element
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Since a learning object may contain text content, we still need some elements to support
such textual formats as paragraph, table, list, and head. Figure 3.2 demonstrates the
structure of element and the attached attributes. In this structure, in addition
to some text elements, the element is used to indicate what kinds of multimedia
are used in this learning object, so the proper tools can be invoked to display the
multimedia files. This element includes three attributes, type, mimeType and uri,
which present the type of the multimedia file and the reference to the file. Moreover, the
element may be used to tag some special texts, such as formulae or algorithms.
However, for the element and element, it is possible to adopt an
existing specification to develop test items. In this schema, QTILite specification from
IMS is imported. This specification is based upon the IMS QTI specification and is the
realization of a subset of that model. It is presented as the entry-level specification to the
full QTI specification, just supporting the question styles of true/false and multiple
choices with single answer.
Figure 3.3 Importation of QTILite Schema
Figure 3.3 demonstrates how the QTILite specification is included in our LOML schema.
The schema file, ims_qtil_rootvip1.xsd, is loaded by the element and the
namespace, qtil, is assigned to reference the QTILite schema. Therefore, the LOML
schema may use any element type from QTILite to define new elements. By adopting the
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specification from IMS, the test items developed for learning objects may be easily reused
by other e-Learning systems. A detailed description about the use and implementation of
OTILite can be found in [Brooks 2002].
3.2 Schema for Metadata
3.2.1 The Design of Schema
There are currently several metadata XML schemas focusing on e-Learning. However,
though those schemas may be used, a specific metadata XML schema should still be
created in this research for the following reasons:
The purpose of most standard schemas having the goal of interoperability is to
allow everyone throughout the world to be able to successfully find and use
learning objects. Therefore these schemas are complex, often with about one
hundred element tags. An alternative is to choose some necessary elements from
them and to build a new schema which will provide a good enough description for
the learning objects in this specific project;
A designer wants to be able to search for the specific topics within the library of
learning objects. To do this effectively, the schema must have a controlled
vocabulary, only allowing certain words to be entered between tags. While this
makes the searches fast and accurate, it is not possible to do this without creating a
unique schema. In fact, we need to add more constraints in our own XML schema
and make the metadata document more meaningful.
However, using a unique XML schema will not significantly harm the interoperability of
the e-Learning system. We choose the tags from the standard schema, so every tag in our
schema is still meaningful to others. A third-party search engine that can handle the XML
metadata documents conforming to the standard schema could also handle ours. In
practice, we selected about 23 tags from the IMS Learning Resource Meta-data
Specification. Figure 3.4 shows the first and second level elements in the tree structure of
the metadata schema:
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Figure 3.4 Structure of Metadata
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1. general Context independent features of the resource
identifier - Globally unique label for learning objects;
title Name give to the resource;
language The human language used by the learning object;
description A textual description of the content of the learning object;
keywords Keywords describing the resource.
2. technical Technical features of the learning object
format Technical data type of the resource;
location A location or a method that resolves to a location of the resource;
3. educational Educational or pedagogic features of the learning object
interactivitytype the type of interactivity supported by the learning object;
learningresourcetype specific kind of resource, such as text or figure;
context the typical learning environment where use of learning object is
intended to take place;
semanticdensity subjective measure of the learning objects usefulness as
compared to its size;
difficulty how hard it is to work through the learning object for the typical
target audience;
4. relation Features of the resource in relationship to other learning objects
kind Nature of the relationship between the resource being described and the
one identified by element;
resource Resource the relationship holds for.
5. classification Description of a characteristic of the resource by entries in
classification
taxonpath A taxonomic path in a specific classification.
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3.2.2 Controlled Vocabulary
Many search engines have a problem with interpreting the content between tags. Each
person will use different words to describe the same learning object. When search engines
try to find useful learning objects, this reduces the accuracy of the search. The best way to
overcome this limitation is to employ a controlled vocabulary. Of course, there will be
elements that allow a text description without controlled vocabulary, such as
element. However, these elements will usually not be used for searching.
They will be used once a search has been completed to enable either the designer or the
student to make a decision about whether or not to use the learning object without
actually looking through it. Whenever possible, it is useful to specify a controlled
vocabulary.
It is desirable that some existing formal vocabularies can be adopted; however, this is not
always possible. In the schema for metadata, three sets of vocabularies are selected to be
used directly to describe the learning objects:
Computing Curricula 2001.This is a joint task force to undertake a major
review of curriculum guidelines for undergraduate programs in computing bythe Computer Society of the Institute for Electrical and Electronic Engineers
(IEEE-CS) and the Association for Computing Machinery (ACM) [CC 2001].
In this curriculum a set of vocabulary has been defined to represent different
levels of topics in computer technologies. In the element, this
vocabulary is used to classify the areas with which the learning objects are
concerned;
Code for the representation of the names of languages.It comes from ISO
639, in which each language is represented by a two-character code. In the
schema, the element adopts those codes to indicate what kind of
language is used;
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Multipurpose Internet Mail Extensions (MIME). MIME defines all the
medium types on the Internet, so that the element can use them to
describe the data types of learning objects.
However, when a formal vocabulary is not available, a set of vocabulary is defined
according to the necessity. For example, the element uses the vocabulary,
{very easy, easy, medium, difficult, very difficult}, to describe how hard it is to work
through the learning object.
3.3 Schema for Content Packaging
In an e-Learning system, instructional content must be collected and packaged in some
electronic form to enable efficient aggregation, distribution, management, and
deployment. The content packaging from IMS may be used to enable the encapsulation of
the required learning resources, simple course structure information, and other supporting
information such as metadata, which promotes the flexibility and interoperability of
learning materials.
However, one of the major weaknesses of the IMS content packaging specification is that
it only supports a simple structure, and does not include any instructional designinformation. Therefore, it is necessary to add new approaches, such as hierarchical
branching, or custom learning paths with conditional branching, if they are required. In
this research, the basic structure of the IMS content packaging specification is adopted,
and then some new features are introduced to make flexible generation of an indivi
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