AbstractDistance learning has taken root, but it will take a big push to get to the next level. A key is to make courseware reusable in creating other courseware and interoperable across a wide variety of platforms on which the courseware is to be presented. In fact, reusability and interoperability are the cornerstones of the emerging distance learning standard called the Sharable Content Object Reference Model (SCORM). In this article, we examine reusability and interoperability for distance learning as embodied in the SCORM specifications. We also outline some important research projects related to SCORM. 1 INTRODUCTIONDistance learning, also called e-learning, cyber education, etc., is the delivery of instructions using network and multimedia computer facilities, and has become an important part of modern education for universities and corporations by complementing traditional in-class education. One of the challenges for distance learning is the creation of high quality course materials (lecture notes, references, tests, etc). While intelligent technology is still under development to automatically aggregate sufficient course materials, it is important to share and reuse well-developed learning objects (i.e., decomposed reusable objects as a course material) to reduce the load on instructors, and to make them available across a wide variety of platforms. Thus, the concepts of reusability and interoperability in distance learning are an interesting issue for education professionals, system developers, and learners. (note: In this article, we use the term “course materials” to refer to lecture notes, tests, references, presentations, etc, of distance learning in general. When discussing reusability, we use the term learning object to refer to a decomposed part of course materials.) In order to achieve reusability and interoperability, standards are needed. The Advanced Distributed Learning (ADL) initiative (http://www.adlnet.org/) first proposed the Sharable Content Object Reference Model (SCORM) standard in 2000. Main contributors to SCORM include the IMS Global Learning Consortium, Inc. (http://www.imsglobal.org/), the Aviation Industry CBT (Computer-Based Training) Committee (AICC) (http://www.aicc.org/), the Alliance of Remote Instructional Authoring & Distribution Networks for Europe (ARIADNE) (http://www.ariadne.eu-org/), and the Institute of Electrical and Electronics Engineers (IEEE) Learning Technology Standards Committee (LTSC) (http://ltsc.ieee.org/). SCORM addresses the following four high-level requirements (http://www.adlnet.org/):
Reusability and interoperability are of interest for the purpose of this article. Reusability can be achieved by using SCORM-compliant authoring tools, which can be used to produce course materials that may be decomposed, shared, and reused among different lectures. Interoperability can be achieved by using a SCORM-compliant Learning Management System (LMS), which also includes a sequence engine to control user interactions. The SCORM 2004 (also known as SCORM 1.3) specification consists of three major parts: the Content Aggregation Model (CAM), the Run-Time Environment, and the Sequencing and Navigation.
2 REUSABILITYIn order to make a learning object reusable, a standard representation of its content and its structures must be observed and enforced. CAM provides such a standard. It consists of three parts: the Content Model, the Metadata, and the Content Packaging. The Content Model defines the hierarchy of learning objects, that is, how a learning object is organized in terms of smaller potions at different levels. The Metadata describes the Content Model and provides an efficient mechanism for content search. The Content Packaging is a definition that allows the content model and structure to be packed into a standard exchangeable file, known as the Package Interchange File (PIF). The PIF (see Figure 1) allows learning objects to be exchanged in a standard form across different platforms on which these learning objects are presented. There are several categories (called, somewhat imprecisely, “levels” in the SCORM specification) of learning objects in the Content Model:
For instance, a picture illustrates that a machine architecture can be stored in a JPEG file, with an HTML file to specify its location and other associated descriptions. The HTML file can be regarded as an aggregation, while the JPEG image file is an asset. An asset does not maintain communication with the SCORM run-time environment. However, with additional control programs, such as Java scripts, learning objects can be packed into an SCO, which follows a communication protocol and interacts with the SCORM run-time environment. A learning activity is a collection of instructional events, with or without references to an SCO. For instance, the instruction can specify a pretest, a lecture, and a final test in an activity for a particular session of a class. Content aggregation is a mechanism which is used to gather different portions of course materials. Aggregation is described in an XML file (see Figure 1) which is read by the SCORM Run-Time Environment when the associated learning object starts.
Figure 1: The SCORM Content Packaging (adapted from SCORM 2004 Specification in http://www.adlnet.org/) For an instructor to find suitable contents for reuse, a search mechanism is necessary. Course materials may contain pedagogical properties, which may not be found by ordinary search engines. One of the remaining challenges for the SCORM specification is the design of a reasonable set of metadata which can be used to precisely and easily describe course materials. According to IMS (http://www.imsglobal.org/), a content package (i.e., a representation of course materials) includes two parts: an XML document which describes the organization of a course object, and a set of physical files which contain learning objects. Usually, each physical content file is associated with an XML file which has the metadata. A few control programs which maintain the communication between a learning object (e.g., SCO) and the SCORM run-time environment are also included in a content package. 3 INTEROPERABILITYThe same learning object must necessarily be available on different computers and software platforms. The specification of SCORM run-time environment provides a standard protocol for learning objects to talk to its underlying Learning Management System (LMS), which is a machine and OS independent platform. The specification of SCORM run-time environment includes the procedures and responsibilities for learning objects to communicate with the LMS, a set of standard application program interfaces (APIs) for communication, and a data model which describes the messages passed between learning objects and the LMS. A sample client-server architecture for the implementation of the LMS is illustrated in Figure 2. Typically, the LMS is installed in a central server, where all of the learning objects and student profiles are stored. Since students login to the server from the client side, it is necessary to install an instruction delivery system on a client computer. The decentralized installation avoids service traffic overload when the computation power of the central server is limited. The procedure for viewing a learning object starts with a launch process by the LMS. After that, controls are passed to the learning object (i.e. an SCO). An initialization is issued by the SCO, followed by a series of invocations to the API, which is handled through an API adapter on the client computer. In some cases, Java scripts are used in the SCO to enable interactions between the user and the learning object. The Java scripts call proper API functions, which check the status of the learning process. Before the SCO is closed, it calls the termination API function to terminate communication with the LMS. While the learning object is presented, the associated multimedia data are retrieved and presented by a Web browser on the client computer.
Figure 2: The SCORM Run-Time Environment (adapted from SCORM 2004 Specification in http://www.adlnet.org/) 4 PROJECTS RELATED TO SCORM AND IMS SPECIFICATIONSA product directory (http://www.imsglobal.org/direct/getproducts.cfm) summarized by IMS provides information on SCORM-compliant and IMS specification related projects. We briefly discuss projects related to SCORM and IMS specifications below. Authoring Tools
Learning Management Systems
5 CONCLUDING REMARKSSCORM 2004 is not widely accepted yet. One of the reasons is its complexity, which is more than 700 pages long and still expanding. The complexity should be hidden from the end users through automated tools and solutions. With the reusable and interoperable course materials, course material developers will be able to design and exchange course materials easily, and students and instructors will benefit from higher quality distance learning. REFERENCES
About the authors
Cite this column as follows: Won Kim, Timothy K. Shih: “On Reusability and Interoperability for Distance Learning”, in Journal of Object Technology, vol. 3, no. 8, September-October 2004, pp. 27-34. http://www.jot.fm/issues/issue_2004_09/column3 |
