STANDARDS
Metadata Standards for Educational Resources Marilyn McClelland, North Carolina Central University
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ach semester, I create Webbased learning experiences for my students by weaving together digital educational resources or learning objects such as videos, images, assessments, simulations, or tutorials. Often I use previously created material, if only I can find it. One current challenge of distributed learning is creating and managing content to facilitate reuse. Instructors as well as students must be able to easily locate existing online content and import it into an authoring system or learning management system. In the 1990s, recognition of the potential economies of reusing educational materials spawned the development of metadata standards for sharing and storing learning objects. Metadata is data that describes a physical or electronic resource and can be used to manage collections of documents, images, and other information in a repository such as an archive or museum. Some metadata elements—such as title, description, subject, and keywords—are similar to those that libraries use to catalog their holdings. Other elements, such as the uniform resource identifier (URI), are specific to a digital, Web-based environment. Metadata can be stored in a digital library or repository that provides services to search or browse for educational materials. The Dublin Core
DCMI created its first metadata standard, the Dublin Core Metadata Element Set, to facilitate search and retrieval of Web-based resources. The American National Standards Institute approved DCMES in September 2001 as ANSI/NISO Z39.85 (www.niso. org/standards/standard_detail.cfm?std _id=725) and, in February 2003, the International Standards Organization ratified the standard as ISO 15836 (www.niso.org/international/SC4/n515. pdf). The current version 1.1 (http:// dublincore.org/documents/dces/) in-
The Dublin Core and IEEE Learning Object Metadata standards facilitate reuse of educational resources.
Metadata Element Set and IEEE Learning Object Metadata are two popular metadata standards that facilitate cataloging, searching, and reuse of such resources.
DUBLIN CORE The Dublin Core Metadata Initiative (http://dublincore.org/) is an organization dedicated to developing interoperable metadata standards for a wide range of purposes. Conceived at a March 1995 workshop in Dublin, Ohio, jointly sponsored by the Online Computer Library Center and the National Center for Supercomputing Applications, DCMI holds conferences, workshops, and tutorials throughout the world. As an open forum, DCMI invites participation from all interested researchers and practitioners. Its DC-General mailing list currently has some 1,500 subscribers from more than 50 countries. DCMI operates a number of working groups and is actively working with the World Wide Web Consortium as well as application developers.
cludes 15 well-defined elements for describing “core” information properties: title, creator, subject, description, publisher, contributor, date, type, format, identifier, source, language, relation, coverage, and rights. Its developers designed DCMES to be simple enough for untrained Webpage authors to use and more extensible than complex formats such as machine-readable cataloging. The standard supports resource discovery across multiple disciplines—including publishing, museum information systems, library science, and knowledge management—and within any type of organization. In addition, through the DCMI Registry, DCMES currently offers definitions in 25 different languages. DCMI provides guidelines for encoding Dublin Core metadata in XML and RDF/XML to enable interoperability across different platforms, languages, and systems. The following example illustrates an XML instance of Dublin Core metadata for a photo created by Charles R. Ward, a chemNovember 2003
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istry professor at the University of North Carolina at Wilmington, and cataloged in the iLumina digital science repository (http://aa.uncwil.edu/dl/): Condensation Charles R. Ward Chemistry This image illustrates condensation of water vapor to liquid on the outside of a glass of water 2001-09-25 example image/jpeg ilumina:611 http://aa.uncw. edu/digilib/chemistry/ general/condensation.jpg Copyright free for non-commercial use. For commercial use, contact the creator. All Dublin Core elements are repeatable. In this example, the identifier is repeated, once with the “ilumina:611” reference number and again using the URI. Elements are also optional; consequently, metadata for a given record may be scant, and repositories are not likely to populate all the fields. As Dublin Core has evolved, DCMI has provided extensions to DCMES— now referred to as simple Dublin Core—to allow for additional specifications. Qualified Dublin Core includes qualifiers to refine the use of an element or to identify an encoding scheme or controlled vocabulary as the element’s source. For example, the identifier tag in the XML code snippet above could be modified to include the 108
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URI encoding scheme: http://aa.uncw.edu/ digilib/chemistry/ general/condensation.jpg Dublin Core has developed a diverse, widespread installation base. For example, the Open Archives Initiative (www.openarchives.org)—an organization that promotes interoperability standards to facilitate the dissemination of content, especially in public research archives—has adopted DCMES as the default for sharing metadata, though it also supports metadata representation in other formats. Other key supporters include the Library of Congress and the National Science Foundation in the United States, Japan’s National Institute of Informatics, the Helsinki University Library, the National Library of Australia, Germany’s Die Deutsche Bibliothek, the National Library of Canada, and the Joint Information Systems Committee and UK e-Envoy in the United Kingdom.
IEEE LOM In June 2002, the IEEE Standards Organization approved its first learning content standard with the release of IEEE Std. 1484.12.1, IEEE Standard for Learning Object Metadata. The IEEE Learning Technology Standards Committee developed IEEE LOM in collaboration with DCMI, the Alliance of Remote Instructional and Distribution Networks for Europe, the IMS Global Learning Consortium, and other organizations. In contrast to DCME, IEEE LOM takes a structuralist approach to metadata creation. Its 60 elements provide a means of developing more comprehensive descriptions of learning objects and providing support for user services. IEEE LOM v1.0 organizes these elements into nine categories: general, life cycle, meta-metadata, technical, educational, rights, relation, annota-
tion, and classification (http://ltsc.ieee. org/wg12/index.html). The “Example of XML Learning Object Metadata” sidebar illustrates an XML instance of two of the categories, general and classification, for “ilumina:611.” As with Dublin Core, all elements are optional, thus there are no required fields and no minimum cataloging requirements. Like qualified Dublin Core, IEEE LOM uses controlled vocabularies to define terms when populating a field. For example, the classification category provides four elements to describe where a learning object falls within a specific classification system: • Purpose. This element indicates the kind of classification used and may have up to 10 different values—discipline, idea, prerequisite, educational objective, accessibility, restrictions, educational level, skill level, security level, and competency. A given learning object can be classified with multiple purposes. • Taxon path. This element provides a term or listing of terms, arranged from broadest to narrowest, that applies to a stated purpose. It includes two subelements: Source specifies the name of the classification system—for example, Dewey Decimal or Library of Congress—and taxon indicates a particular term within the taxonomy. A taxon path can have an alphanumeric identifier as well as an entry, or textual label. • Description. This element concisely but thoroughly describes the resource in accordance with a stated purpose. • Keyword. This element provides keywords and phrases descriptive of a learning object’s stated purpose. The ability to create complex hierarchical relationships facilitates interoperability with browser and search services. However, it can also pose dif-
Example of XML Learning Object Metadata The following XML code snippet implements two of the nine LOM categories, general and classification, for “ilumina:611”: 611 Condensation en This image illustrates the condensation of water vapor to liquid on the outside of a glass of ice water. states of matter physical change gas to liquid iLuminav1.0 Individual Learning Resource LOMv1.0 Discipline Chemistry:iLumina Modified Library of Congress Chemistry Subject Heading Chemistry/General/ iLumina Classification Structure The complete XML instance is available at http://turing.bear.uncw.edu/iLumina/meta_xml.asp?rid=611.
ficulties for a novice cataloger. A few hours of training can greatly improve cataloging skills, but this learning curve can inhibit content creators who are seeking to quickly develop their own metadata or automatically create it using software.
echanisms exist for converting data between Dublin Core and IEEE LOM. However, aggregating data from different repositories
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is easier if they use the same controlled vocabularies or the mapping between such vocabularies is known. For example, data can be lost in the translation of LOM to simple Dublin Core because DCMES does not reflect some LOM elements. Even if their sources are known, mapping between controlled vocabularies is often not well defined. Appropriate controlled vocabularies continue to evolve as users and developers gain experiences with these standards. ■
Marilyn McClelland is a professor of computer information systems in the School of Business at North Carolina Central University. Contact her at
[email protected].
Editor: Gary Robinson, 85 East India Row, Apt. 18C, Boston, MA 02110;
[email protected]
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