A
Design
of
Subject Model for Web
-
based Education System
Anandi Giridharan and P. Venkataram
Protocol Engineering and Technology (PET) Unit, ECE Department,
Indian Institute
of
Science, Bangalore
-
5600
12,
INDIA,
E
-
mail: (anandi,pallapa} @ece.iisc.ernet.in,
http://pet.ece.iisc.ernet.in/pallapa
Abstract
With the rapid growth of the Internet users and
its
applications there has been considerable interest in Web
-
based
education systems that facilitates distance education. In this paper, we propose a Subject Model for Web
-
based
Education system. The designed model uses a
tree with multiple links. Each link weight has been derived from the
conceptual relations, among the concepts of the subject. The designed modular tree with multiple conceptual links was
very useful in guiding diverse students through the courseware.
1
Introduction
The Internet is the largest, most powerful computer
network in the world. As more and more colleges,
universities, schools, companies, and private: citizens
connect to the Internet either through affiliations with
regional not
-
for
-
profit networks or by subscribing to
information services provided by for
-
profit companies,
more possibilities are opened for distance educators to
overcome time and distance to reach students. With
access to the Internet, distance educators and their
students can use: Electronic mail (e
-
mail), Bulletin
boards, World
-
Wide Web (WWW). When using the
Internet for educational purposes, there is no difference
between local and distance education. The classroom
becomes a virtual classroom and the location becomes
transparent structure. Intelligent Tutoring Systems have
opened the way for the emergence
of
Web
-
based
Adaptive Educational Systems (AES). The classification
of AES based on
[1]
their goal, is due to: Curriculum
Sequencing (or instructional planning), Intelligent
analysis
of
student solutions
,
Interactive problem solving
support, Example
-
based problem solving, Adaptive
presentation
[2]
technology, Adaptive collaboration
support
.
Adaptive navigation support technology is to
support the student navigation and orientation in
hyperspace by changing the appearance of visible links.
In particular, the system can adaptively sort,
[3]
annotate,
or partly hide the links in the current page to make easier
the choice of the next link to proceed.
Adaptive Web
-
based Education Systerns usually
enable content and navigation adaptation, by altering the
link structure and the node contents of the hypertext that
contains the educational material. Hypertext is a
promising means for constructivist learning, but its use
poses problems that require curriculum sequencing,
adaptive presentation and adaptive navigation AES. Such
hypertext
-
based systems allow moderation of user-
control versus user guidance in navigation and provide
for better user orientation. Furthermore, ill
-
structured
domains pose several important problems that are hard
to solve for systems that provide problem
-
solving
support and analysis of student solutions. Domain
modeling should be based on flexible knowledge
structures and incorporate concept dependencies.
However, the issue of effectively establishing
non-
taxonomical concept relationships is hard to resolve.
Detailed information on the user is required. In the
following section we present, a Web
-
based system
architecture. Section
3,
explains a proposed Subject
domain model. Simulations are presented in Section
4.
Finally in Section
5,
we present the conclusions.
Figure
1.
Web
-
Education Architecture
0-7803-7600-5/02/$17.00@2002
IEEE
32
2
Web
-
Education Architecture
The components of web
-
based architecture are shown in
Figure
1.
The components are:
0
Adaptive User Interface.
User Model.
0
Subject domain Model.
Adaptive User Inte$ace:
The user logs on to access the
course material through the web server, which launches
adaptive interface. Adaptive Interface then accesses the
database containing the user model and domain models,
selects the appropriate information for this user according
to
hisher user model and returns the information to the
user via web server.
User
Model:
The user model
[4]
deals with knowledge
about each module. User knowledge level is analyzed and
User model determines the module and the concept
available to each user. If the knowledge of the user is
superior to the weightage of the module and concept, then
user is presented with appropriate module and concept
relavent to user's knowledge level.
Subject domain Model:
Structure of the subject domain
depends on weighted links which are organized as set of
Modules associated with relevant concepts. Student
should have at least minimal expertise to access certain
modules. We explain
our
approach to adaptive web
-
based
courseware by means of an example courseware on
"
Communication Protocol
"
,
so
that a student can easily
find the most relevant information depending on
hisher
needs.
2.1
Some
of
the existing Web
-
based education
systems.
Web
-
based AES inherits from two earlier kinds of AES:
intelligent tutoring systems
.
(ITS) and adaptive
hypermedia systems. Traditionally, problems of
developing AES were investigated in the area of
intelligent tutoring systems
[5].
ITS use the knowledge
about the domain, the student, and about teaching
strategies to support flexible individualized learning
and tutoring. Adaptivity was one of the goal features
of any
ITS.
Existing adaptive Web
-
based systems can
be divided into three groups: adaptive information
systems which serves personalized information online
like
AVANT1
[6],
adaptive filtering systems which
helps user to find relevant
"
drops
"
in the ocean of
available information like
ifWeb
[7]
and adaptive
educational systems. AES is the biggest group: more
than half of the existing adaptive Web
-
based systems
are AES. Number of existing Web
-
based AES such as
ELM
-
ART, CALAT, WITS or Belvedere were
developed on the basis of earlier standalone
ITS.
3
Proposed subject domain model
In this section we discuss the design of the subject
domain model for web
-
based education system. The
design is based on the module prioritization scheme. The
given subject or topic may be divided into a set of
Modules. The modules are interlinked based on the
subject material placements in each of the modules. Each
module is further divided into a set of associated
concepts.
3.1.
A
Method
of
subject classijkation
The placement of subject material in the database is an
essential,
so
that a student can easily find the most
relevant information depending
on
hisher needs relevant
to his knowledge level. Psychological models often
mention three sources of knowledge competent teachers
use. First, the teacher is an expert in the subject matter
(e.g., helshe knows about the concepts of the domain and
their interrelation, is able to criticise solutions of
problems, answer questions, give examples, and far
more). Second, teachers know how to teach something
(e.g., they use strategies to teach a concept, they know
when to use a certain teaching material
or
presentational
method). Third, teachers build a model of the students'
knowledge. This allows teachers to adapt their teaching
methods to different students or groups of learners.
Basically, the knowledge base is built on a conceptual
network with different types of units which are lessons,
sections, subsections, and concepts. Several types of
information are associated with each concept. Besides,
each unit has prerequisites (units that the student should
be familiar with before working on the unit), and
consequences (possible outcomes and effects on other
units). The tests and prerequisites are weighted
according to their importance for a unit. Integrating
interactive tests in a
WWW
learning environment is one
more valid way of getting information about the learner's
knowledge. The diagnostic component stores the
knowledge about several types of tests. Each test in the
test base can be connected to multiple concepts, rated on
difficulty and on relevance for a concept. Depending on
the difficulty and the relevance of a test, a student's
solution has different impacts on the learner model. The
learner model stores the preferred settings of a learner
and the domain units a learner worked on. Teach texts:
With every concept a teach text with three levels of
detail is defined. The first level contains only basic
information about a concept. The second level explains
some concepts used in the first stage in more detail and
the third stage gives detailed information and advanced
hints. Structure tests to represent an appropriate degree
of difficulty, in terms of degree of comprehension:
Basic knowledge (facts, definitions, identify
concepts
andor ideas studied
-
70%.
Application of concepts and lor ideas in
situations nearly identical to examples worked
on in class or in homework
-
20%.
33
New applications or uses of concepts andor
ideas, or their use in situations previously
unseen (tests for thoroughness of understanding
10%.
3.2
Weights
of
subject
modules.
Generally given topic or course may be divided into set
of Modules. Let
S
be the course which is divided into m
modules,
S
=
(MI
,
M2, M3....Mm). These modules has
been interlinked, based on the subject
rnaterial
placements in each of the module. The modules are
arranged in the order of degree of difficulty.
DD(MJ
<DD(M2)
.......<
DD(M,), where
DD
is degree of difficulty
of the module. The degree of difficulty of a
modlule can
be given as weight,
Wi =x*i
,
i
€
l....m-1. Where value
x
depends on the level of difficulty of the modules, that
may vary from
10
for high school level,
20
for graduate
level,
50
for post graduation level and
so
on. The
interlinked weight increases
as
the modules gets more
advanced. All the subject modules have been placed in
ascending order are interlinked. For example, let subject
S has 4 modules,
S=
{MI
,
MZ, M3, M4} and the: subject
domain model
is
build at the post
-
graduate level, then the
weights of modules,
MI
,
M2,
M3, M4
are W1=50, W
=I
00,
W3=l
50
and W4=200 respectively.
3.3
Module-concept relation
Each of the modules of
S
are further classified into the set
of concepts where the concepts and its related description
along with example has been furnished. For example, Let
Mi be divided into
Ki
number of concepts, them Mi
=
Cil,CiZ, ....... CiKi. The interrelated association among the
concepts are based on priority in which they will be
displaced or transfered to the users for their access. The
concepts of a module have been interlinked based on the
degree
of
difficulty of the subject material in the concept.
The degree of difficulty of a concept
is
calculated
as
follows:
C,ij=Bij+Aij+Nij
Where B9=basic knowledge content coefficient of
concept
j of the module i. Aij=Application coefficient of
concept
j of the module
i.
Ni, =New applications
coefficient of concept j of the module i.
Figure
2.
A
Subject Module Mi with its associated
concepts.
Module and its concepts relation linked with help
of
conceptual weights are depicted in figure
2.
3.4
An
example
In this section, we illustrate theoretical subject domain
module for placing subject material Web
-
based
Education as discussed in previous sections. A subject
S
is
divided into modules and each module is further
classified into set of concepts
.
I
I
Figure
3.
Hypothetical course model.
Intermodule relation and inter
-
conceptual relation as
been set up based on the order in which material to be
presented to the users. We have chosen multi
-
link
conceptual graphs for the placement of entire subject
material
S.
Figure
3.
illustrates a conceptual graph for
the hypothetical course
S.
When the user visits the
Module
Mi having weightage Wi, that is relevant to his
knowledge level, and tries to access Concept,
Ci,
appropriate node designed for his knowledge level using
adaptive navigation technique
[8]
is presented to him.
This navigation is not in the preview of this paper.
4
Simulation
We have considered the subject material of
communication protocols to construct the domain model.
Figure
4.
describes the modules of the course and Figure
34
5.
clearly indicates Conceptual tree [9] meant for diverse
users based on their knowledge levels
.
b
1
1
3
I
5
6
1
a
9
I I I
I
Figure
4.
Modules and concepts of the subject:
Communication Protocol.
Subject domain model for Communication Protocol
course has been prepared based on degree of difficulty of
the modules and concepts
[lO][ll] based on degree of
difficulty of the modules and concepts. The Simulation
program was developed by using Java for computing the
weights
of
the modules as well as concepts. The subject
contents of modules and concepts with interlink
information has been optimally placed in the
multilink
conceptual graphs as shown in Figure
5.
The entire
course material occupies around 100 Kilobytes storage
space. The goal
is
to achieve better performance that
is
suitable for diverse users.
5
Conclusion
A
prototype design of Subject model for Web
-
based
Subject Material has been presented. Design structure
allows the diverse users to offer relevant navigational
possibilities. The designed modular tree with multiple
35
conceptual links were very useful in guiding diverse
students through the courseware.
Figure
5.
Communication course design model.
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