Sharable Content Object Reference Model (SCORM)

In recent years, many e-learning standards have been developed. The Sharable Content Object Reference Model (SCORM) is an aggregated specification for asynchronous distance learning, organized by the Advanced Distributed Learning Initiative (ADL) (http://www.adlnet.org/). SCORM contains the definitions about the meta-data of learning material, Content Aggregation Model (CAM) which defines how to organize a course into a tree-like structure called Activity Tree (AT). Fig. 2.6 shows an example of AT. It is a structure that provides the hierarchical organization of learning content. According to SCORM 1.3 specification, an AT is structured by a set of clusters. A cluster is an organized aggregation of activities consisting of a single parent activity and its first level children, but not the descendants of its children. The cluster is considered to be the basic sequencing building block. The parent activity of a cluster will contain the information about the sequencing strategy for the cluster.

The status information of all child activities will be collected and can be used to sequence these activities in the structure.

Fig. 2.6: An activity tree with clusters

2.4.1 The Sequencing and Navigation (SN) Specification

The SCORM Sequencing & Navigation (SN) Specification is based upon the Instructional Management System (IMS, http://www.imsproject.org/) Simple Sequencing Definition Model. It provides a profile about information of specific behaviors between activities and restrictions while learning an activity. The Sequencing Definition Model (SDM) defines the following categories: Sequencing Control Modes, Sequencing Rules, Limit Conditions, Auxiliary Resource, Objectives, Objective Map, Rollup Controls, Selection Controls, Randomization Controls and Delivery Controls.

(1) Sequencing Control Mode (SCM):

The Sequencing Control Mode (SCM) allows the content developer to determine how navigation requests are applied to a cluster and how the cluster’s activities are considered while processing sequencing requests. Table 2.3 describes the SCM that may be applied. Sequencing Control Modes can be applied to any activity in the AT and multiple modes are enabled to create combination of control mode behaviors.

Nevertheless, the Sequencing Control Choice, Sequencing Control Flow and Sequencing Control Forward Only modes will have no effect if applied to leaf activities.

Table 2.3: The description of Sequencing Control Mode (SCM)

SDM Description

Sequencing Control

Choice

Indicates that a Choice navigation request is permitted to target the children of the activity

29 Sequencing Control

Choice Exit

Indicates that the activity is permitted to terminate if a Choice sequencing request is processed.

Sequencing Control

Flow

Indicates the Flow Sub-process may be applied to the children of the activity.

Sequencing Control

Forward Only

Indicates that backward targets (in terms of Activity Tree traversal) are not permitted for the children of the activity.

Use Current Attempt

Objective Information

Indicates that the Objective Progress Information for the children of the activity will only be used in rule evaluations and rollup if that information was recorded during the current attempt on the activity.

Use Current Attempt

Progress Information

Indicates that the Attempt Progress Information for the children of the activity will only be used in rule evaluations and rollup if that information was recorded during the current attempt on the activity.

(2) Sequencing Rule:

The IMS Simple Sequencing Specification (IMS SSS) employs a rule-based sequencing model. The behaviors between activities are defined by Sequencing Rules.

Sequencing Rule is composed of a set of conditions and a corresponding action. The structure of sequencing rule is:

if [condition_set] then [action].

The conditions are evaluated using tracking information with the activity. The action of sequencing rule will be triggered if its condition-set evaluates to true. There are three kinds of sequencing actions SCORM proposes: Precondition Actions, Post-condition Actions and Exit Actions, which describe different learning strategies.

(3) Objective:

IMS SSS proposes a mechanism of objectives of each activity for sequencing propose. Each learning objective associated with an activity will have a set of tracking status information which is used to decide which sequencing decision should be triggered according to student’s current learning progress. Two kinds of learning objective are defined in IMS SSS: Local Objective and Global Shared Objective. The Local Objective is only referenced by one activity; however, the Global Shared Objective can be shared by sets of activities. Therefore, activities may have more than one associated local objective and may reference multiple global shared objectives.

Fig. 2.7 shows an example of objectives. All objectives except Objective 5 are local to their associated activities; Objective 5 is a global shared objective shared between Activity AA and Activity BB.

Fig. 2.7: An example of objectives (4) Rollup Rule

Cluster activities are not associated with teaching materials; therefore, there is no direct way for learner progress information to be applied to a cluster activity. The

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IMS SSS defines the way of how to evaluate the learner progress of cluster activity.

The structure of rollup rule is:

if [condition_set] True for [child activity set] then [action].

The conditions of rollup rule are evaluated against the tracking information of the included child activities, and a corresponding action will set the cluster’s tracking status information if the conditions are evaluated to true.

2.4.2 Tracking Model

The tracking model is a collection of dynamic sequencing state information associated with each activity in the activity tree for each learner. Tracking model elements will be updated to reflect learner interactions with the currently launched content object during a learning experience. It defines the following sets of tracking status information:

(1) Objective Progress Information: describe the learner’s progress related to a learning objective.

(2) Activity Progress Information: describe a learner’s progress on an activity. This information describes the cumulative learner progress across all attempts on an activity.

(3) Attempt Progress Information: describe a learner’s progress on an activity. This information describes the attempted progress on an activity. Fig. 2.7 shows the Tracking Models for an Activity Tree.

Fig. 2.8: The tracking models

Currently, more and more researches about constructing an intelligent tutoring system based on SCORM standard. However, the processes of building an activity tree and defining sequencing behaviors are very complicated for teachers, because the formats of meta-data and Simple Sequencing are described by XML. The functionality within a lesson or between lessons is hard-coded whether based on linear or an adaptive model. It means teachers must edit lots of XML files for building a course; definitely, it will bring more burdens to teachers and limit the reusability of individual learning objects (SCOs). It also limits the ability to create new or custom content structures from the same instructional materials. Therefore, in addition to the tools for editing the SCORM-compatible content packages, the mechanism for the SCORM learning sequence construction is important as well.