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ABOUT THE PROJECT

Introduction
THE PROJECT  |  REUSABILITY   |  WHAT, HOW AND BY WHOM  |  REUSABLE DESIGN   |  REUSABILITY FACTORS  |  GRANULARITY

GRANULARITY

Granularity of digital learning resources refers to size, decomposability and the extent to which a resource is intended to be used as part of a larger resource.

A related term is aggregation level , which is used in IEEE Learning Object Metadata (LOM) to describe “the functional granularity” of a learning object. The IEEE LOM Standard ( IEEE LOM, 2002 ) is used in the learning technology community and is incorporated into other specifications and standards [ Standards Primer ]. IEEE LOM offers the following scale for aggregation level:

  1. The smallest level of aggregation, e.g. raw media data or fragments.
  2. A collection of level 1 learning objects, e.g. a lesson.
  3. A collection of level 2 learning objects, e.g. a course.
  4. The largest level of granularity, e.g. a set of courses that lead to a certificate.

A point made by the LOM scale is that file size may not be tightly coupled with granularity. For example, an image (LOM aggregation level "1") may be several megabytes in size, whereas a lesson that incorporates that image using a link (LOM aggregation level "2") may be only a few kilobytes.

Granularity and Content Models

Granularity, or aggregation level, is important in defining and determining reusability. For an image, reusability means the ability to use the entire image in another setting. For an entire online course, reusability often refers to the ability to use parts of the course.

The Learnativity Foundation has developed a content model or aggregation model ( Wagner, 2002 ) that is useful for describing granularity.

Learnativity Aggregation Model ( Wagner, 2002 )

Granularity
Explanation
Content Asset Raw media: Images, text snippets, audio clips, applets, etc.
Information Object A text passage, Web page(s), applet, etc. that focuses on a single piece of information. It might explain a concept, illustrate a principle, or describe a process. [Single] exercises are often considered to be information objects.
Learning Object In the Learnativity content model a Learning Object is a collection of Information Objects that are assembled to teach a single learning objective [see below].
Learning Component A learning component is a generic term for things like lessons and courses that typically have multiple learning objectives and are composed of multiple learning objects.
Learning Environment “Learning Environment” is a catch-all phase for the combination of content and technology with which a learner interacts. Thus a course written in a course management system is a learning component, but a deployment of the course in a live Course Managemnet System at a particular institution (with a particular enrollment policy, help center, library reserve system, etc.) is a learning environment.

The Learnativity Aggregation model blends pedagogic and technical perspectives. The idea of an information object is based on earlier work on learning and structured writing by Robert Horn ( Horn, 1993 ).

The term learning objective (used to define a learning object) is an instructional design concept that derives from the work of Robert Frank Mager ( Mager, 1997 ), Robert Gagne ( Gagne, 1985 ), Walter Dick and Lou Carey ( Dick & Carey, 1996 ) and others. A learning objective is a single measurable (or verifiable) step on the way to a learning goal. Learning objectives say what a learner is expected to do or learn and how an acceptable level of achievement will be verified. They can come from the psychomotor, affective and cognitive domains and can range from knowledge and comprehension to synthesis and evaluation (see Bloom's taxonomy ( Bloom, 1956 )).

Themes found in Clark's writings( Clark, 1998 ) and in a corporate training white paper published by Cisco Systems ( Barritt & Lewis, 2000 ) are developed in the Learnativity model. It has gained considerable acceptance in both the training and education communities. The following diagram, reprinted with permission from ( Wagner, 2002 ), shows the above model in graphical format.

Learnativity Aggregation Model (Levels of Granularity)

Granularity, Decomposability and Reuse

Each level of granularity has a different inherent degree of ability to be decomposed into more granular pieces, and each level of granualrity has different inherent expectations for reuse. In addition, reuse often refers to components of resources rather than to the entire resource. It is therefore necessary to scope judgments concerning reusability to the granularity of the resource being examined. The following table is intended to aid in this regard.

Decomposition and Reuse as a Function of Granularity

Granularity
Decomposability
Reuse
Content Asset Indecomposable Content assets are reused as is, possibly with modifications in presentation and style.
Information Object Decomposable into content assets. Information objects are normally reused as self-contained units. In authoring situations, sometimes, content assets are extracted and reused as well.

Learning Object

Decomposable into content assets and information objects Learning objects are meant to be reused as self-contained units. Sometimes, information objects or content objects are extracted from a learning object.
Learning Component Decomposable into learning objects Learning components can be reused in their entirety, but it is suspected that most reuse of learning components uses only parts of them, usually learning objects.
Learning Environment Decomposable into content, technology and processes that support learning The components of learning environments can be reused, but learning environments are not reusable objects in the sense being discussed here.

Granularity and Standards

Several common learning technology standards deal with aspects of granularity.

The Learnativity model maps onto the IEEE LOM aggregation level scale with both assets and information objects being assigned an aggregation level of “1”, Learnativity learning objects having aggregation level “2”, learning components aggregation level “3” and learning environments aggregation level “3” or “4.”

The most widely implemented set of specifications intended to allow learning content to be developed independently of a particular delivery platform is the Sharable Content Object Reference Model (SCORM) , a collection of specifications and standards that is documented and maintained by the Advanced Distributed Learning initiative. SCORM includes a content aggregation model that features:

  • Assets
  • Sharable content objects (SCOs)
  • Content aggregations

SCORM assets are content assets and information objects in the Learnativity model. SCOs are self-contained learning objects or learning components that meet additional technical requirements needed for interoperability with learning delivery platforms. A SCORM content aggregation contains assets, SCOs, information on the order in which these should be delivered and metadata about entire aggregation and its individual components. In the Learnativity model, a SCORM content aggregation could be a learning object or a learning component. SCORM uses a technical specification developed by the IMS Global Learning Consortium to define the format for content aggregations.

Matrix - Reusability Framework as a Function of Granularity

The following table provides a matrix that summarizes the above discussion, and also relates granularity to three reusability factors - Design, Metadata and Interoperability.

Reusability Framework as a Function of Granularity

Granularity Definition Decompos-ability Reuse Design Metadata Interoperability Standards Dominant Products
Content Asset Raw media: images, text snippets, audio clips, applets, etc. Indecomposable Content assets are reused as is, possibly with modifications in presentation and style. The key issue for content assets is separating presentation from content. Contextual dependence should be avoided. Basic metadata and information about rights will allow assets to be cataloged and reused. Technical information may also be important. In practice, content assets are often labeled only with a title and identifier. Text and pure HTML are standardized formats for content assets, although HTML produced by most authoring tools is not standards conformant. XHTML is an improvement.

Interoperability is improved by associating appropriate metadata to a content asset.

Content assets are usually edited and displayed using common authoring suites, plug-ins and browsers. For widest use, it is best when no plug-in is needed, or when a plug-in is freely available, automatically downloaded and widely in use, e.g. Flash™ or Acrobat Reader™. Products, Plug-ins and formats can be community-specific, as in those needed to produce and display MathML.
Information Object A text passage, Web page(s), applet, etc. that focuses on a single piece of information. It might explain a concept, illustrate a principle or describe a process. (Single) exercises are often considered information objects. Decomposable into content assets. Information objects are normally reused as self-contained units. In authoring situations, sometimes, content assets are extracted and reused as well. For information objects, separation of content from presentation is important, and it is also important to avoid cross references that entangle the content with the structure, pedagogy and context. Basic metadata is important for information objects, but it may also be important to say something about the educational level and style of an information object. It may also be important to facilitate proper attribution by including the identification of the author(s) within metadata. Information objects are similar to content assets. For applets, Java™ is considered a standardized format by some, although it has many platform and versioning issues. There are specification and standards that specifically address test questions. Information objects are similar to content assets in that they generally require a single application to edit and a single plug-in or application to display. The products involved are usually not specific to learning, although it is possible to use learning-specific authoring tools to produce information objects. Look for products whose output can be edited by more commonly available tools.
Learning Object A collection of Information Objects that are assembled to teach a single learning objective. Decomposable into content assets and information objects Learning objects are meant to be reused as self-contained units. Sometimes, information objects or content objects are extracted from a learning object. The considerations for information objects apply to learning objects. Additionally, there is a danger of hard-coding navigational elements and unnecessarily tying the object to a particular pedagogical approach or assumed context. Contextual information becomes very important for learning objects. A title and description may not be enough to determine what they are about and who they are for. Guides for instructors and learners may be needed, and for adaptation, technical information and documentation become important. It is always a good idea to be explicit about terms of use. SCORM and IMS specifications are relevant to learning objects. Learning objects whose structure is expressed in XML, even if proprietary, can usually be transformed for use in other environments. Metadata is always important. Working with learning objects may require authoring and editing tools that are built for that purpose. As with information objects, the output is paramount for interoperability. On the delivery side, learning objects that are not tracked require standard server technology, but if data is to be exchanged between the learning object and the delivery system, then products like course management systems and learning management systems must be used to have any degree of interoperability. Assessment engines are also important for learning objects that include quizzes.
Learning Component A learning component is a generic term for things like lessons and courses that typically have multiple learning objectives and are composed of multiple learning objects. Decomposable into learning objects Learning components can be reused in their entirety, but it is suspected that most reuse of learning components uses only parts of them, usually learning objects. As the aggregation level increases, reuse shifts to component reuse. Therefore issues of separating pedagogy, structure and content become more crucial for reuse. Pedagogical approach and contextual dependence become the limiting factors for reusing or repurposing learning components in their entirety. Many learning resource catalogs list courses and modules and only provide basic metadata. More detailed contextual information is helpful, as is information that guides the user. It should be noted that most metadata associated with a learning component applies to the component as a whole and not to learning objects, information objects or content assets contained within it. Learning components are similar to learning objects. Learning components are similar to learning objects although they may rely more on course management technology. If a learning component (e.g. a course) can only run on a particular course management system, it is not very interoperable.
Learning Environment “Learning Environment” is a catch-all phase for the combination of content and technology with which a learner interacts. Thus a course written in a course management system is a learning component, but a deployment of the course in a course management system at a particular institution (with a particular enrollment policy, help center, library reserve system etc.) used by learners is a learning environment. Decomposable into content, technology and processes that support learning The components of learning environments can be reused, but learning environments are not reusable objects in the sense being discussed here. Learning environments may be designed for a specific context and pedagogical approach or may be more general. The more general ones are those that are reusable. For them, it is important to avoid cross-linking of components of the environment. Information about a learning environment is rarely encoded using a standardized metadata record. Nonetheless, it is important to provide a description, information about intended users, rights and technical information, and proper documentation. The standards relevant to learning environments are those relevant to IT infrastructure. Learning environments must integrate with registrar systems, library information systems, content and knowledge management systems, etc.

 

 

 

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