A learning object is a unit of digital resource that can be shared to support teaching and learning (Wiley, 2000; Wiley & Edwards, 2002). Learning objects are used for knowledge sharing in education (Cohen & Nycz, 2006; Collis & Strijker, 2003; Singh, Hawkins, & Whymark, 2007). Along with the increasing use of online and blended teaching/learning systems, such as WebCT as well as e-portfolio systems, learning objects become increasingly valuable and, at the same time, the management of learning objects repository becomes complicated.
There have been metadata standards for learning objects, such as those proposed by Dublin Core (2007), IEEE LTSC (2007), and IMS Guide (IMS, 2006). These standards are used to represent individual learning objects at the collection level, which is similar to library catalogue systems. However, to use learning objects to support teaching and learning at the knowledge sharing level for a specific field, knowledge schema must be applied to the learning objects repository for the domain (Harman & Koohang, 2005; Koohang, 2004). This is because learning objects can be organized in a variety of ways depending upon complex intra-context and inter-context (Wiley & Edwards, 2002). When a virtual learning objects repository is huge and is distributed on the Internet, the use of meta-data and keywords only to search the needed learning objects is inefficient and ineffective since much potential associations with various learning aspects are bypassed (Mustaro & Silveira, 2006). This has lead to approaches to Semantic Web applications that model the relationships between learning objects using formal ontologies (Sicilia & Lytras, 2005).
While meta-data of learning objects describe the artifacts of learning objects that are shared by diverse domains, an ontology represents a knowledge domain that shares the relationships of learning objects within a specific context. There has been moderate literature on ontologies associated with learning objects (e.g. Snae & Brueckner, 2007; Zouaq, Nkambou, & Frasson, 2007). However, few research reports have provided explicit generic structures of ontologies for knowledge sharing. Our motivation for this article is to propose a generic organizational structure of learning objects for the domain of pedagogy design based on the premise that ontologies can help people to better share knowledge (Welty, 2003), and to demonstrate the usefulness of the proposed resource organizational structure for pedagogy design.
In this article we first discuss the key features of ontology of learning objects repository. We then propose a generic structure of ontology for the pedagogy design domain and place the emphasis on ontology development for pedagogical knowledge sharing. Through an example of ontologybased learning objects management system for pedagogical knowledge sharing, we demonstrate the effectiveness of ontology for learning objects repositories.
Ontologies of Learning Objects Repository
Ontology in the Context of Learning Objects
Ontology is a science that studies explicit formal specifications of the terms in the domain and relations among them (Gruber, 1993). In the general philosophical term, an ontology is a specification of a conceptualization (Gruber, 1995; Guarino, 1995). In the learning objects field, an ontology is typically a network of semantically related learning objects for a specific learning or instructional domain. An ontology allows people to share common understanding of the subject domain of learning objects.
According to Resource Description Framework (RDF) (W3C, 2007), a primitive ontology is a triple containing a subject, an object, and a predicate (relationship) (see Figure 1a). Its special form, which represents reciprocal relation of learning objects (dual subject and object), is shown in Figure 1b. …