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Using Ontologies to Support the Sharing of Learning Resources

Michael Gardner
Last modified 16 Jan, 2007
Published 16 Jan, 2007
Michael Gardner describes the development of DELTA, a tool for practitioners which enables them to submit, search and retrieve distributed resources, based on standardized metadata and identified pedagogical contexts. This article will be of interest to those following the current debates around pedagogic ontologies versus folksonomies.

Introduction

This work arose from the UK JISC (Joint Information Systems Committee) funded desk-study in e-Learning Models [1] undertaken by a consortium led by the University of Essex. The study identified the need for a tool which could support practitioners in sharing and searching for learning resources, based around the pedagogical context for the use of each resource. DELTA was subsequently funded by JISC as part of their Distributed e-Learning Programme [2]. It builds on the use of semantic web technologies and the use of pedagogic and subject domain ontologies to uniquely classify resources, and support the user when searching for new resources. DELTA is currently being evaluated in a large-scale regional pilot [3] in the East of England.

A definition of ontologies – from Wikipedia [4]

In the field of computer and information science, Wikipedia defines an ontology as a data model that represents a domain and is used to reason about the objects in that domain and the relations between them. An ontology will represent the particular meanings of terms as they apply to a domain. For example the word ‘card’ has many different meanings. An ontology about the domain of poker would model the ‘playing card’ meaning of the word, while an ontology about the domain of computer hardware would model the ‘punch card’ and ‘video card’ meanings. This is important because although humans are capable of using the Web to carry out tasks such as finding the Finnish word for "car", to reserve a library book, or to search for the cheapest DVD and buy it, a computer cannot accomplish the same tasks without human direction because web pages are designed to be read by people, not machines. Ontologies are a building block for the future semantic web, which is a vision of web resources that are understandable by computers, so that they can search and perform actions in a standardized way.

Overview of the approach

The fundamental aim is to provide an architecture to allow teacher and learner-controlled materials to be shared, and to "grow context" with sharing. In the case of learners the aim is to allow work that has been commented on, or even assessed, to be indexed as "tertiary courseware" [5], and shared with other learners. In the case of teachers, the vicarious materials could be case studies of teaching approaches. DELTA is a system which allows distributed resources to be submitted, searched and retrieved, based on standardized meta-data. Extensibility is a key issue, in that it should be possible for new resources to be added and shared by the learning community. This is achieved by providing a managed meta-data server, which contains the schemas for the sharable resources. DELTA also contains a number of subject ontologies which support the user in categorizing and finding new resources. At the heart of the system, all resources are categorized by a pedagogic ontology. This ontology supports practitioners in contextualizing their needs within a set of core pedagogic principles, which will affect their choice of learning resources for any given learning activity. Figure 1 illustrates a screen from the Delta resource wizard, which guides the practitioner through the process of classifying a resource against its pedagogical context.

Figure 1. Delta wizard

Figure 1. The Delta wizard.

DELTA classifies resources according to the 26 resource-types defined by RDN/LTSN [6]. The resource meta-data schema is also based on a subset of the UK-LOM [7], although it is possible for users to extend the schema by adding relevant elements from other schemas. The DELTA tool is available as both a web service and as a web application. It is available on SourceForge at [8].

The basis for the core ontology

An ontology is a formal representation of a knowledge domain. It is the key component to using the semantic web approach for searching repositories. The relationships described as part of the ontology can allow the user to search on the basis of semantically related terms. It is this technology that is being adopted by DELTA to represent the pedagogical knowledge that can support the selection of appropriate educational resources. The main classes for the core pedagogical ontology are based upon the 16 pedagogical approaches identified by the JISC funded desk-study [1], the RDN/LTSN resource types and the Mayes’ conceptual framework and three stage model (see [5]). The resources are classified according to the nature of the teaching, learning or assessment activity they were designed (implicitly or explicitly) to support. This division is based on the Mayes’ three stage model, where he identifies activities associated with bringing learners into contact with other people’s concepts, "doing" something (i.e. constructive activities) with those concepts , and discussion and reflections with others from which new concepts could arise. The Mayes’ activities also map onto the pedagogical approaches, which are characterized by the sub-concepts of Generic Learning Activity (GLA), Context, and Roles. Thus the core pedagogic ontology, provides the necessary relationships to map resources to pedagogical approaches.

The semantic web approach

The use of ontologies and the semantic web for e-learning is well described in [9]. This is further expanded by Aroya et al [10], who identify the need to capitalize on the use of (1) semantic conceptualization and ontologies, (2) common standardized communication syntax, and (3) large-scale service-based integration of educational content and functionality provision and usage. The DELTA system goes some way to meeting these aims. It also builds on the notion of vicarious learning [5] with the intention of "growing context" around the use of learning resources by the community. This is about capturing and reusing other learners’ experiences, particularly through annotations attached to specific resources. This is related to the work by Yang et al [11] which explores the concept of ontology enabled annotation and knowledge management.

Semantic web technology can significantly improve the effectiveness of digital resource sharing. By using an ontology inference service, searching no longer need be constrained to matching the content only, but also by inferring the true meaning of the concept it is possible to retrieve all knowledge equivalent resources. The current DELTA system incorporates a number of additional subject-domain ontologies which can be used to extend and enhance the search capability within DELTA. The main challenge in constructing an educational subject ontology is in adequately defining its scope and granularity, and how it should be represented to the user.

The aim of the subject ontology is to provide subsuming inferences - so that when searching for resources with a particular subject it will retrieve not only resources within that subject but also subsuming resources. For example, searching with the term "knowledge representation" will retrieve not only resources with the subject "knowledge representation", but also "semantic web" subject resources. From this point of view, the subject ontology acts as a recall device, where instead of explicitly defining the subjects to be searched, implicit subject resources derived from ontology inferences will also be retrieved.

The subject ontology will also improve the relevance of retrieved resources. Every subject defined in the subject ontology is uniquely identified by a URI, and each URI consists of a namespace to represent the subject domain it belongs to and a local name to represent the concept in its domain. Here the ontology acts as a precision device, improving the relevance of resources retrieved.

In general, ontology construction requires expert understanding of a given domain. Currently DELTA contains around 20 subject ontologies that have been extracted from the well-known community maintained portal Wikipedia (using a tool developed by the project). Plus 3 specialised subject ontologies in "core skills", education and computer science have been constructed by the team.

In order to provide interoperability between other heterogeneous e-learning digital libraries, a means for harvesting metadata from, and exposing DELTA metadata to, other heterogeneous systems is needed. In order to achieve such integration, DELTA includes an OAI-PMH protocol [12] to expose it’s data to other services, plus a harvesting tool to extract data from other services.

Current project status and research issues

So far we have completed two iterations of the development of the DELTA system. The first version was evaluated through a simple expert walkthrough which focused on usability issues, and we are now completing a much wider evaluation of the second version in the EERN regional trial [3]. This has focused on a range of quantitative and qualitative measures particularly on the pedagogical value of the ontologies within DELTA, and the sharing of heterogeneous resource types. A key factor was the ability of DELTA to grow context around the sharing of best practice and educational resources by the practitioner community.

The pilot consisted of three main partner sites, University of Essex, Suffolk College, and University of Hertfordshire. Each main partner also had associated colleges, for example, the University of Essex also included Writtle College and South East Essex College (SEEC). Each pilot site was designed to provide a differing learning context (courses and users) to fully test the overall objectives. In the case of the University of Essex, the focus was on Teacher Training (Certificate of Higher Education Practice). The University of Hertfordshire focused on a particular learning resources (lecture material) created by the use of a JISC developed authoring tool (Smirk), whilst Suffolk College looked initially at resources available on a VLE (WebCT), for use in vocational courses. Both the University of Hertfordshire and Suffolk College focused on ‘Core Study Skills’ as their main curriculum area. An evaluation programme run by the University of Luton was created to assess the performance and value of DELTA within the EERN pilot trials.

In this pilot, DELTA has proved easy to use and most practitioners recognised the potential benefits of the pedagogical approach inherent in DELTA. However they often found the concept of ‘sharing’ a challenging one. In general, there is a poor culture of sharing within HE and FE. The matter is compounded by the fact that to share also means creating the necessary metadata, which is not a simple or quick task. The metadata harvesting capability in DELTA has improved this situation but is limited by the lack of suitable repositories to harvest metadata from, and does not address the ‘pedagogical’ metadata. Further, the searching and use of learning resources is not a continual process. Most lecturers infrequently create or update their lecture material (perhaps only once a year). Also, the notion of ‘continuous improvement’ of quality through reflection and assessment is not a universally adopted one. It is clear that the main issue is not technology, but winning the hearts and minds of the practitioners. Until the ordinary teacher recognises the true value and benefits of e-learning, it is in danger of remaining partially used, misunderstood and undervalued.

There are also clear research issues which arise from this approach particularly in the area of community defined ontologies and the "folksonomy" approach used by such tools as Flickr and Del.icio.us [14], [15]. In these systems a folksonomy of terms or labels that describe online content is generated autonomously by the user population. For example, if I upload my holiday photos to Flickr then I can describe the photos with textual labels such as ‘beach’, or ‘castle’, etc. This then enables other users to find my pictures if they are looking for a particular subject area (eg. castles of Britain). This type of social classification can work well for certain kinds of information, yet raises several issues particularly where a knowledge domain needs to be validated by some kind of information architect.

We are also investigating ways of automatically classifying users’ resources and making them available to their online communities through the use of social-networking tools. For more information on these new projects, see the eProfile and ResourceBrowser project websites at http://www.essex.ac.uk/chimera/projects.html

All of the software developed in these projects is available on Sourceforge. If needed, we can also provide access to our own trial versions of the tools – please contact the author (mgardner@essex.ac.uk) if you would like to discuss this further.

Michael Gardner is Deputy Director of Chimera, the Institute of Social and Technical Research at the University of Essex. His research explores the use of new social software tools and the semantic web to support collaborative and online learning.

References

[1] JISC e-Learning Models Desk Study.

[2] DELTA project description on the Jisc web site

[3] JISC EERN: The East of England's Educational Resource Network.

[4] Definition of ontologies on Wikipedia

[5] C.J.H.Fowler and J.T. Mayes. Learning Relationships from Theory to Design. Association for Learning Technology Journal, 1999, Vol. 7 No.3, 6-16.

[6] LTSN-RDN.

[7] UK-LOM.

[8] Sourceforge repository.

[9] Sampson, D. G, Lytras, M. D, Wagner, G & Diaz, P (2004). Ontologies and the Semantic Web for E-learning. Educational Technology & Society, 7(4), 26-28.

[10] Aroyo, L, & Dicheva, D (2004). The new challenges for e-learning: the educational semantic web. Educational Technology & Society, 7(4), 59-69.

[11] Yang, S. J. H, Chen, I. Y. L, & Shao, N. W. Y (2004). Ontology enabled annotation and knowledge management for collaborative learning in virtual learning community. Educational Technology & Society, 7(4), 70-81.

[12]Open Archives Initiative

[13] JISC Distributed e-learning programme.

[14] Flickr

[15] Del.icio.us

 

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