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Article Excerpt
This article presents a general framework for building concept-based digital course libraries. The framework is based on the idea of using a conceptual structure that represents a subject domain ontology for classification of the course library content. Two aspects, domain conceptualization, which supports findability and ontologies, which support reusability of learning resources are incorporated uniformly in the library architecture. The suggested framework implies a layered information structure of the library content consisting of three layers, each capturing a different aspect of the information space--conceptual, resource-related, and contextual. We present an environment, TM4L (Topic Maps for Learning), aimed at supporting the development and use of concept-based digital course collections. The new ISO standard, XML Topic Maps (XTM), that provides a paradigm for organizing, retrieving, and interchanging information on the Web, is used in the proposed framework to implement concept-based digital course libraries.
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E-learning involves the use of new information and communication technologies and media to deliver, support, and enhance online learning, education, and training. The challenge it faces is to allow different modes of communication between learners and instructors, various ways of the provision of learning content, and enhanced support for online instructional activities. E-learning support systems' developers inherit from the achievements and lessons learned in the areas of traditional and intelligent pre-internet educational systems. However, the Web poses new challenges and opens new horizons to e-learning technologies. Typical e-learning scenarios involve preparing online instructional materials by instructors (authors) and extensive use of online learning materials by students (learners) in completing their learning tasks. Thus the success of e-learning applications depends crucially on the amount of effort that is involved in both developing educational materials by authors and retrieving relevant learning resources by learners. Important derivable questions then are: how to organize and classify the learning content and how to share, reuse, and exchange existing instructional units. In this article we discuss these questions in the context of one strategic category of e-learning applications, digital course libraries.
Digital course libraries are applications that contain instructional materials to assist students' learning in a specific discipline (course) and support students' course-related work (e.g. projects, assignments, etc.) that is aimed at reinforcing their knowledge. They play a vital role in out-of-class learning, and especially in project-based and problem-based learning. A good digital course library should provide learners with powerful and intuitive search tools that allow them to efficiently access sufficient amounts of relevant resources so that they can spend less time for searching and more time for learning. It should provide instructors with powerful authoring tools that support efficient creation, modification, and update of educational materials.
There are two main groups of problems related to using existing courseware, specialized educational collections, and educational portals intended to provide informational support for learning, as course digital libraries. The first group is related to the findability of online information: the information is often organized in such a way that the provided links are not intuitive and it is hard to find a needed piece of information. The broadly exploited hierarchical organization typically does not support "horizontal" navigation, that is, navigation to conceptually related information, relevant examples or different viewpoints. Another essential problem related to the efficient search of resources relevant to a specific learning task is that students are often unaware of the complete context of the task and need help in getting oriented in the conceptual structure of the subject domain. The second group of problems is related to the reusability of existing repositories of learning resources by instructors, which in turn concerns the existence of both shared agreement on their content and standards-based representation.
In this article we discuss the issues of findability and reusability of information in the context of digital course libraries. We address these issues by incorporating in the course library architecture a meta-layer--semantic layer, based on the conceptualization of the course subject domain. The fundamental idea is to build those libraries as both concept-based and ontology-aware repositories of learning objects.
Conceptualization can support topical finding of resources and learner's understanding of the specific subject domain (by enabling exploration of related domain concepts). Subject domain conceptualization has been long used for knowledge representation in intelligent tutoring systems (ITS). More recently, concept structures play a central role in adaptive hypermedia (AH) applications--for content fragmentation and structuring (Eklund, Brusilovsky, & Schwarz, 1997; Brusilovsky, Eklund, & Swartz, 1998; De Bra & Calvi, 1998; Murray, Gartner-Piemonte, & Kelleher, 2001), and in concept-based course support or learning support systems--for domain knowledge representation and information structuring (Vassileva & Deters, 1998; Greer et al., 1998; Aroyo, Dicheva, & Velev, 2001; Brusilovsky & Vassileva, 2003). These applications use the conceptual structure of a specific subject domain to organize digital material but they mainly support interconnected material and typically little or no references to external related documents. In the case of AH, the content is shareable (the generated dynamic web pages can be viewed in any browser), but not reusable and exchangeable. In the case of teaching and learning support systems, instructional materials have normally system-specific internal representation and therefore are not shareable, reusable, and interoperable.
The benefits of educational use of ontologies, however, have been only recently recognized (Mitrovic & Devedzic, 2002; Dicheva & Aroyo, 2002; Devedzic, 2003). Ontology is a well founded and broadly agreed upon system of concepts in a particular subject domain together with the relationships between those concepts. Thus specialized subject ontologies can be used as a semantic backbone for e-learning repositories. By providing common vocabularies for domain knowledge representation, ontologies are essential for instructional content "interaction." Courseware units can only be shared, reused, and exchanged among different authors if the authors agree on the vocabulary used in their construction. In addition, ontologies facilitate machine readability of web content. Ontology-aware digital course libraries can be implemented as ontology-based collections of standard learning objects (of right granularity) with standard technological support for describing, relating, retrieving, and presenting their content. In...
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