Disaggregation and reutilization of Sharable Content Objects Álvaro Reis Figueira1, Michael Kaufmann1,2 1
LIACC-Departament of Computer Science, FCUP, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal 2 School for Higher Education ESE de Paula Frassinetti, Rua Gil Vicente, 138-140, 4000255 Porto, Portugal
[email protected],
[email protected]
Abstract. The need to produce high-quality digital educational contents for web-based instruction raises the problem of trying to meet individual students’ needs and the extreme cost of that approach. Digital educational repositories may be a facilitator to this problem by presenting a set of already produced material that can be reused. However, the granularity problem on the educational material that is stored in the repository may still hamper this method by hiding important learning material in the shell of a more contexted learning object, which is, therefore, less reusable. In this article we propose and describe a method to find and disaggregate learning packages such that reusability of the material stored in such a repository may be increased. Keywords: Learning Objects, Disaggregation, Reuse, SCO.
1
Introduction
Digital Educational Repositories have become one of the most wanted developments for teachers and educators. The possibility of reusing and easily adapt existing learning material is without doubt one of the most expected development yet to-be. As is becoming generally accepted, a sound pedagogy should meet the learner’s needs and preferences [1], which implies that learning environments have to be customized and personalized. However, matching learning environments and, specially, the educational contents with each student’s demands is much more expensive than serving all the students with one learning environment and with the same sequence of the same educational contents. This situation is presented and the “predicament of the knowledge economy” dilemma [2]. Instructional designers realize that creating different online courses for different student’s takes to much effort [3, 4] and do need the help from a repository of educational contents which can be searchable, accessible and from which they can get material to be used and adapted for their course design. The specification from IMS defines digital repositories as being any collection of resources that are accessible via a network without prior knowledge of the structure of the collection, and which may
hold assets or meta-data that describe assets. Moreover, the assets and their meta-data do not need to be held in the same repository [5]. Recently, the trend is not only to include resources in such repository – by resources we mean texts, images or videos – but also aggregations of such material presented as learning objects (LOs) [6, 7, 8], with well-defined objectives, targeted to specific audiences and presenting its contents in a pre-defined and sequential way, as prescribed by the SCORM 2004 model from the ADL initiative [9]. Therefore, the contents of the repository can now be seen as a library for modules of learning material, each covering a special feature, or unit of learning, and of a particular subject, which can then be reused in a different course, or even in a different context. In this particular, more and more educators advocate that the delivery method of education is not the most important part of the learning process, but the context is [10]. However, as showed by several authors [11, 12] the capacity of reuse of one LO is indirectly proportional to its size, i.e., to the contextual involvement it has. This property poses the problem of deciding on the granularity of the LO. That is, should the LO be given a greater context, and therefore, minor chances of being reused, or should it be given greater chances of reusability by taking less of context? In this article we take the view that LOs are created according to the personal experience of the teacher, or course designer. Therefore, we must admit that in a repository there can be LOs with greater or lesser context, aggregations or simple LOs. In this base we propose a method for retrieving LOs which are aggregated in packages. This technique is automatically applied in a query to the repository which returns a collection of LOs, whether they stand alone or are part of an aggregation, in both cases, provided that they meet the query criteria. As we regard any SCO as being undividable, the scope of disaggregation of a SCORM package is limited by the number of its containing SCOs, created during the authoring process. An extension to our approach, would be the disaggregation of large SCOs into their single assets (text blocks, images etc.), as proposed in [13], although this technique relies on structure and content ontology aware content [14] which might be restricted to certain content types.
2
Repositories of Learning objects
Given the requirements of a digital repository in higher education, there can be distinguished three types of digital content objects: SCORM Content Packages, Websites and Documents. In our opinion, all three types of digital content objects can and should coexist within the same repository, although the present document will focus on the reuse of SCORM Content Packages. SCORM Content Package. A Sharable Content Object (SCO) is a standardized form of a reusable learning object. SCOs are, in fact, a collection of digital assets and meta-data, describing these assets. Typically, several SCOs are assembled (packed) into larger units of learning, a SCORM Content Package, ideally, to fulfill a distinctive learning objective. These Packages are designed in such way that any
SCORM compliant Learning Management System can launch and communicate with the SCOs in it, while keeping learner information and interpreting instructions that tell it which SCO comes next. Websites. Although educationally valuable, most websites cannot be exported and delivered as a package. A good repository should not be restricted to “imported”, local content but should also allow the inclusion of remote content. Thus, meta-data of external websites should be created and included into the repository contents, for instance, by means of annotated bookmarks [15]. Documents. Academic publications like journal articles, PhD theses, book sections or articles in conference proceedings play an important role for any academic research work and should be includable into an academic repository. Other types of documents to be included are technical instructions or manuals. Documents should be included in full text (pdf) whenever possible or by means of an abstract and an external link, which will typically lead to the full text document or an indication on how to purchase the full text document.
3
Disaggregation of SCORM Packages
The disaggregation of a SCORM Package is an essential step onto the possible reuse of parts of the package and can be divided into two sub-problems: The reuse of sub-Packages. According to [9], any learning activity (technically, any in an branch) can reference a Sub-Manifest. In other words, it is possible, to create a SCORM Package by the aggregation of several autonomous SCORM Packages. SCORM Package B Imsmanifest.xml Search & Select
SCO SCO Asset SCO
Fig. 1. Reuse of sub-Packages
This first case straight forward as disaggregation consists basically in the analysis and isolation of the sub-Package’s elements. The discovery (and ultimately, the delivery) of the necessary elements is facilitated by the sub-Manifest, which serves as an “inventory of resources” and which will also be the root Manifest of the extracted Package on delivery. The reuse of SCOs. The reuse of SCOs can be a far more difficult task.
First, there usually is no (sub-)Manifest, which can be simply reused for re-packing and delivery. Secondly, there may not exist sufficient meta-data. As described in [9], “a SCO should be independent of its learning context” and “can be described with SCO Meta-data”. In the case of insufficient meta-data, we currently do not see any practicable solution to derive meaningful meta-data for a SCO from other (child-, sister- or parent-) elements in the SCORM Package – above all, having in mind its independence of the learning context. We envision one possible workaround by the use of content structure and domain ontologies [14]. For the time being we will only regard properly characterized SCOs, with a minimum meta-data quality. One possible way to measure the quality of meta-data is to define a minimum set of attributes, which will include certain LOM attributes such as , , and . Finally, there has to be made an extra effort in identifying and isolating all necessary assets, which will be used by the SCO. The tag is the starting point for that process of collection of assets. In its absence, one could consider a source code parsing of the actual html-files contained in the SCO. The simplified prospected workflow for the reuse of SCOs is illustrated in fig.2.
SCO
Search & Select
Re-Pack
SCORM Package XYZ Imsmanifest.xml
Deliver
SCO
Fig. 2. The reuse of SCOs
3.1 Considerations on Storing, Indexing and Searching To discover complete SCORM packages as well as containing SCOs, the underlying indexing mechanism has to be aware of the Activity Tree Structure of the SCORM
Package, along with the respective meta-data. To prevent redundancies and inconsistencies, SCORM Packages should only be disaggregated on-demand, that is, temporarily, during indexing and on delivery. Every SCO and every Asset should be stored only once in the system. Our approach is to analyze and resemble the hierarchy of SCOs in the Activity Tree of each package and hence, to create an ordered tree on top of a relational database. The main benefit of this approach is the availability of reliable database management systems and tested mechanisms such as full text indexes. Other approaches, like XML storing and querying are, though, thinkable [16]. 3.2 Presentation of Search Results The presentation of the search result indicates clearly the dependence between the SCOs and their parents by presenting them in a tree-structure. The end-user has the possibility to choose the maximum depth of search in order to minimize the response time of the system. However, this limitation can also be used to improve the system’s efficiency.
Fig. 3. Possible Search Results Presentation
Fig. 3 illustrates the situation of presenting several links in response to the query "Dijkstra Algorithm" posed to the Repository. In this example we have the following situations: 1. A SCORM Package ("Dijkstra's algorithm") 2. A SCORM Package ("Java Programming Course") 3. A SCO that is present in package 2) 4. A SCORM Package ("The History of Programming") 5. A SCORM Package ("Dijkstra's algorithm Course") that is a sub-package of 4) 6. A SCO that is present in package 5) We also want to stress that even detected a SCO that meets the query criteria, what is returned by clicking on its link is always a package. In the case of links 3 and 4 the correspondent SCO is returned in the shell of a newly created SCORM Package. 3.3 Delivery of sub-packages or SCOs In the output screen of a query to the repository, if the user chooses one sub-package by clicking in its reference, then it has to be disaggregated from the packet-container and delivered. However, if a SCO is chosen, then it has to be delivered in the shell of a new-built package such that can easily be adopted for reuse in a unit of instruction. This process comprises a number of steps for the creating of a valid SCORM Package: 1. A new Manifest has to be assembled for the newly created package containing the wanted SCO; 2. All assets belonging to the selected SCO have to be collected; 3. The new package has to be compressed in the proper archive format (PKZip v2.04g (.zip)). This process of disaggregation, creation and delivery of packeges is done on-the-fly and on-demand.
4
Conclusions
In this paper we presented a classification of content objects for a repository in higher education into SCORM content packages, websites, and documents. To facilitate and extend reusability of SCORM content, we proposed the disaggregation of SCORM packages into their Sub-Packages and SCOs and the later re-use in a different context. Issues of efficient storage of the activity structures in a tree representation and its presentation were raised and explained with examples. Our next step is the creation of a realistic set of learning resources and an evaluation of the proposed technique for disaggregation. Furthermore, we plan to create a repository prototype for a first expert assessment of the usefulness. Acknowledgments. The authors want to thank Fernando Ventura for an early review of the article and for the enlightment given on many aspects.
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