A Layered Approach to the Re-Use of Content and its Presentation

Dr Enrico Canale, Head, Courseware Development Services, Teaching, Learning and Research Department, Information Division, The University of Melbourne, 3010. Email: enricodc@unimelb.edu.au

Mr Albert Ip, Managing Director, Digital Learning Systems P/L, Melbourne, 3104. Email: albert@dls.au.com

Keywords

SCORM, Sharable Content Object, Style Sheet, Mosaic Effect, Dynamic Appearance Model, Reusable Learning Object

Abstract

This paper deals with techniques for overcoming the mosaic effect - an impediment to the sharing of content, and proposes layered re-use as a conceptual framework for solving the problem.
The mosaic effect occurs when a course is built by sequencing Shareable Content Objects (SCOs) from a variety of independent sources. Because SCOs have their own individual "look and feel", courses made up of SCOs from different sources suffer from inconsistent presentation styles and interfaces in the format of the learning content. To overcome the mosaic effect, it is necessary to separate content from its presentation. Two techniques have been put forward as solutions to the mosaic effect in the SCORM environment. The first is the Dynamic Appearance Model (DAM) and the second is SCORM with Style-Sheet Support (SCORM-SSS). While the DAM proposes content to be encoded in XML and uses XSL transformations for correct rendering, SCORM-SSS is based on content in HTML and proposes course related style-sheets to ensure the desired course presentation.
This paper develops the concept of layered re-use in which the re-use of content and content structures is governed by specifications appropriate to the content level (e.g. SCORM, IMS QTI specifications) and the re-use of “look and feel” properties and their application throughout a course is governed by HTML-based specifications applied at the display level. In layered re-use terms, for any one course there may be many content models within the content layer and for a particular user or cohort there is a single display model.
The advantages of adopting layered re-use include, a) ease of technical implementation (at scale and wide scope), b) low impact on course development work-flows, c) ease of maintenance against growing complexity in course design and re-design and d) it supports the DAM and SCORM-SSS developments as complementary approaches to overcoming the mosaic effect.