Synchronous Navigation Control for Distance Learning on the Web

Introduction

Albatross: a WWW-based distance education system
- A WWW browser
- Overview Map: an organized road map of the whole course material
- Guide Tool: logging and prerequisite constraints
- Notebook: public and private notes associated with individual documents
Does not consider the instructor/learner relationship as a whole
Synchronous navigation
- Concepts
- Roles and responsibilities
- Architecture and protocol

WWW as a medium
Navigation problems
- Disorientation
- Cognitive overhead
Other missing issues
- Interaction and communication among instructors and learners
- Logging of users' learning behavior
- Assessment

Various techniques have been proposed
But most are biased in favor of learners
- Learners: active
- Instructors: passive or even invisible
- Learner-centric
Instructors must play a more positive and active role
- On-line guidance
- Discretionary during, not prepared before learning progress
- Only a fashionable bulletin board?

Instructor-oriented navigation control
- Group
- Instructor
- Learner
Advantages
- Disorientation is decreased
- Cognitive overhead is eased
- Interaction is improved
- Adaptability is enhanced

Simple client-server architecture
Inadequate for our needs
- Inter-client communication
- Stateless
- Non-permanent connection
Introduce a new master/slave model

Client: A program that establishes connections to send requests
Server: A program that accepts connections to serve clients' requests
Group: A logical collection of on-line clients
- Browse on the same set of documents
- Synchronous navigation behavior
Master: A client that acts as a group leader
- by instructors, moderators, leaders, or peer-tutors
Slave: A client that acts as a passive group participant
- by learners, followers, or onlookers

Access to a new object identified by an URL
- By keying in a new URL
- By clicking on a hyperlink
- By selecting a bookmark/hotlist item from within the browser
Access to a visited object.
- By clicking on back/forward toolbar icons or menu items.
Horizontal and vertical scrolling.
- By using function keys or scroll bars
Highlights on special texts or graphs
- By positioning or dragging the mouse

Mechanism concerns protocols and procedures
Policy concerns enforcement of synchronization rules between a pair of master and slave.
Distance education values more at learner autonomy in its nature
Avoid exceeding synchronous control over slaves
Separation of the mechanism from the policy
- "Synchronization level" agreement
- Allows more flexible learning behavior
- Makes self-paced learning possible
- Assistance, rather than confinement
For example, novices and experienced users

Group repository interface (No. 1-5 in the previous figure)
- Creation, deletion, and query
- Maintenance issues
Per-group interface (No. 6-9 in the figure)
- Connection establishment and release between individual master/slave pairs
Synchronous navigation interface (No. 10-14 in the figure)
- All synchronous navigation control activities
- Most important

Retrieval and display of common documents
Direct data transmission (No. 10).
- The master first packages up hypermedia data
- And then transfers them directly to slaves
URL notification (No. 11)
- Notify slaves the URL of common documents.
- Performs better in some cases
URL notification with proxy location (No. 11 with PROXY field filled)
- The master has fetched documents via the proxy
- And then tells slaves to fetch them via the same proxy.

To aid slaves with on-line and real-time guidance
Synchronous document scrolling (No. 13, using SCROLLTO field)
Mouse positioning with text comments (No. 13, using POSITION field)
Common highlights and/or handwriting on documents (No. 13, using BEGINDRAW/NEXTDRAW fields)

Motivation: distance learning
Manual hypermedia presentation
Automatic demonstration if navigation scripts are provided
Part of an Intelligent Tutoring System (ITS)
- Capable of adapting navigation paths to individual's learning behavior and circumstance