Using a High-Level Language to Describe and Create

Using a High-Level Language to Describe and Create Web-Based Learning Scenarios M. Rodr´ıguez-Artacho, M.F. Verdejo, J.I. Mayorga, M.Y. Calero Departamento de Ingenier´ıa El´ectrica, Electr´onica y de Control Universidad Nacional de Educaci´on a Distancia, Madrid Spain e-mail: fmiguel,felisa,nmayorga,[email protected]

Abstract An approach to web-based educational authoring, separating content from structure is presented. The paper focuses on PALO, a SGML derived language, to define instructional templates. On one hand these templates are a way to organize learning material with a particular purpose, on the other, they provide high-level specifications related to structural, navigational and interaction properties for the final product. The system supplies a compiler to parse PALO instructional templates, generating automatically a web environment.

1 Introduction Networking technologies in education have been implemented with a variety of approaches, from building very simple web environments to quite comprehensive reconceptualizations such as the Virtual Campus metaphor. These technologies have also been embedded in the framework of Distance learning Institutions, with different scope and purposes: either to improve their prevalent independent study model, as an occasion to introduce classical methods such as multipoint teleteaching, or as an opportunity for promoting new learning methods based on collaboration and social knowledge construction.

able. On the other, equipment and bandwith for synchronous audio/video communication are not as affordable as it would be desirable. These constraints have to be taken into account. The newest technology can be used for pilot studies and prospects of innovation, but the approach for a large-scale implementation require facing practical issues from the very beginning. At this point it would be important thinking whether new technologies would actually help to improve or create new learning situations for students and teachers, or if we are just moving or replicating the same problems and difficulties found in traditional teaching. In this paper we present a system to build learning environments. The work described is an approach to WWW educational authoring to be used mainly in a one-to-many scenario to support a high number of distance students. The system improves the authoring tasks and provides room for interactive study processes. The rationale behind is to gradually move from the production of paperbased learning material specially designed for independent study to a more flexible authoring process. Two key design principles are level of abstraction and reusability. Our approach provides authors with means to designing learning material and paths at an instructional level, using pedagogical building blocks such as ”introduce an activity”, ”give a definition”, “give an example”, “offer a hint” or “look for prerequisites ”. Reusability is guaranteed in two ways: domain knowledge description is a separate component. Contents from these components can be selected, combined and structured for a particular learning purpose. Furthermore a structure is an object that can be defined at a generic level and stored in a library for further use.

Open Universities usually share a situation in which large scale and robust solutions are needed to handle a high number of registered students, at least in the undergraduate courses, with a quite limited tutoring staff. On one hand, the rate teacher/students can be up to 1/500. With These two principles are not new, they have been widely these human resources a personalized tutoring model is proposed, from the field of Instructional design[5] [7] [4] not viable even if the communication technology is avail- , educational multimedia [6] as well as from the field of

Session 13a2 software engineering [1].Designing and building educa- rest of instructional material into a separate instructional tional software from scratch has largely proved not to be component. Elements in these two components are didaca scalable approach. tically related, for instance an example illustrates a concept, or a problem has to be solved by applying a method. We provide a way to specify these components using an entity-relationship model. The specification model has 2 Objectives two levels, (i)a meta-level where the number of components, and their abstract definition (i.e. the kind of elFocusing on teachers, the objective is to provide them ements for each component and their relationships ) are with facilities to prepare learning materials at an abstrac- specified. The outcome is a generic model. (ii) a deftion level, at least comparable to the one they are used inition level, where particular descriptions for a domain to when working with traditional media. Our approach can be built as instances of a generic model. For example proposes to separate the authoring process in two kind of we have defined a generic model to describe a set of protasks:(i) building conceptual models to describe a target gramming courses. The generic model includes a contentdomain and (ii) defining views and learning paths on the matter component holding entities of two types concepts domain models, for attaining specific learning purposes. and activities, and an instructional component with entiThe authoring system supplies a framework, with both ties such as problem, hint, example, question and solumodeling tools and a library of generic components, to tion. A course in Program Verification has been described using this generic model. The content-matter component carry out the following tasks: includes concepts such as pre-post specification or invariant, and activities such as to verify, satisfy precondition to define generic models in order to specify a domain or to derive. Further details about our domain modeling description for learning purposes. These generic approach are given in [3]. models can be instantiated to fit in a particular matInstructional Templates are a way to organize learning ter. material with a particular purpose. A template can capto define structured templates embedding learning ture a learning approach such as learning by being told or trajectories learning by doing, and a learning path such as fixed order, guided tour, or free exploration. Our proposal is to use to create a document combining two operations (i) SGML to define these kind of templates. SGML stands selecting a template to instantiate (ii) filling the infor Standard Generalized Mark-up Language. It uses a stance with objects from the domain models descriptive mark-up to create types of hypermedia docufinally, to generate automatically a web-based envi- ments with a predefined structure. The expressive power ronment from the instantiated template by means of of SGML is based on the capability to create a variety of Document Type Definitions (DTD’s) each one generating a compiler. a different type of document with its own structure and components. If a document belongs to one of the defined The following section describes briefly the domain mod- types, a special purpose program (a parser) can process els and discusses in more detail the structure and features the document according to a particular type and check of generic and instantiated templates. whether all the elements required for that document type are indeed present and correctly ordered.

   

We have identified types of documents to support distance learning, analyzing a variety of learning materials currently provided to students. For each type we have defined a template. These templates are described as DTD´s using a language called PALO, derived from SGML. In Learning material usually includes a content matter struc- a first stage of the project we are providing authors with tured description together with questions, examples, fur- three kind of templates to produce web-based scenarios ther explanations, problems to be solved, suggestions for for students to carry out: further study, etc. We propose to encapsulate the content matter description into a contents component, and the

3 Domain models and Instructional Templates

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A

Guided-tour study of a Course containing a related to embed domain objects, are shared between temscheduling of the recommended work during the plates and, thus, have a similar behavior. The description semester language is composed by a group of structure dependant tags and a group of domain model related tags. Tag atSelf-assessment, mainly proposing exercises for tributes also play an important role on defining some other each of the relevant topics of the matter aspects of the final environment. The system includes also an editor to create a document from a template. Finally, a A small individual project PALO compiler (paloc) can process an instantiated template and build a web environment with the structure, conAuthors can select one of these templates, and filled it tent and features described in the document.

 

with objects from a domain model. For each one of these The following points describe in more detail the features instantiated templates, our system generates a web-based mentioned above. environment. Next section describe the key features of PALO, the language provided to define instructional templates.

Structure of the web environment

4 The PALO language Learning environments, including structure and contents can be specified as hypermedia documents using a formal language. It is well known that mark-up languages like SGML provide powerful mechanisms to embed structured descriptions as well as heterogeneous objects [2]. Furthermore, this approach provides a very rich set of tools to parse and process these documents.

Instructional template structure is defined by a set of tags to describe parts and subparts of a document. These tags have attributes, one of them is a name to identify each partition. Templates have their own structure, but the final web page layout does not differ so much between templates, in the sense that generated web-based scenarios have the same frame appearance. A web page shows two frames. An index is build from the structure tags. The compiler creates a scrollable index menu, located on the left frame, and the selected item will appear on the right frame.

Generic Instructional templates, defined as DTD´s in PALO, a mark-up language, are high level descriptions of web-based material. The language has to provide mechanisms,usually tags or tags’ attributes, to express the following aspects:



(Figure 1) shows a snapshot of the web environment generated from a guided-tour template. The index appears on the left and on the right the content of the selected part. The content in this case is a text, with hypermedia links. On the the bottom part of the right frame tree navigational buttons appear: the first one goes back and the other two Structure and navigational model including style and allow to scroll between menu items. presentation

 Contents and references to the domain model  Degree of interactivity for a remote o local usage  User access and tracing Other features have to be supported by the compiler, specially those related to handle mathematical notation in order to process text files associated to some objects of the domain models. PALO provides a library of DTD’s, each one describes an instructional template. Some of the tags , specially those

Using references to domain model objects The domain models identify and characterize the subject matter elements. These elements can be selected and included in a document to create the content, using two type of tags:

 A reference to an entity described by a tag called elemento

 A reference to a relationship described with a tag called relacion

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Figure 1: A compiled Structured Document creates a hypertext web environment elemento identifies an entity of the Domain model. Entities are referenced by a set of attributes that identify them inside the domain model. The name of Object A (Figure 2) is err1, it belongs to Instructional domain and is typed as error category. Tag elemento is divided in two parts, the reference to the element itself and another one called enlaces that can contain both more recursive references to elements and relationships (In Figure 2, part 1 of element A and part 2 of element C).

Introduction An introduction to Program verification An introduction to First Order Logic A common error on this problem is the one called mismatch error exercises are proposed. 1 Two One related to first order logic B and other one related to postconditions this 2 Could hint D help you to solve this exercise? . Content section Exercises section

Figure 2 shows an instructional template in PALO ready to be compiled. It contains structure tags like tema, subtema and seccion that define menu items on the left frame of the compiled web environment as shown in Figure 4. When clicking on the menu item, the right side of the frame loads seccion content (the errores section) . PALO document of Figure 2 contain four hyperlinks to domain objects. This recursive capability allow to create Figure 2: A PALO instructional template different linked tours through the learning environment. Objects A and C have also an enlaces tag, thus allowing to nest other objects related to them. As shown in Figure 2, part 1 proposes two examples (B,C) related to ment and are defined using a tag called respuesta. A A object A. Also, exercise C provides a hint to solve it (Ob- respuesta produce an HTML form with a text or LTEX editor. When submitted, the student answer is stored in ject D). our data base.

Interactivity of the web environment User tracking The system allows to send answers to proposed exercises or activities by mean of a component called answer. An- User tracking is defined by the traza attribute of strucswers can be embedded anywhere in a structured docu- tural and domain objects, as seen in Figure 2. This prop-

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Session 13a2 erty can be set independently on each element, thus providing a mechanism to trace only those components of interest at a given time. In the example, objects A and C are traced and objects B and D are not.

5 The Compiling Process PALOC is a SGML based parser. From a PALO template and the domain model, our compiler creates a web environment. (Figure 3). PALO provides for simple word processing features like itemizes, bold and italic faces. Objects, however, have a more sophisticated treatment because they can hold LATEX mathematical expressions. (See an example in objects B and C of Figure 4). Objects are translated to HTML using LATEX2HTML translator.

A 1

C 2 B

D

PALO Templates + Compilation Strategy 3 Domain Model

Strategy 2 Strategy 1 Learning Scenarios

Figure 3: The compiling process of an Instructional Template

Figure 4: A compiled web environment

We have given the choice of using a tele-learning environment instead of the paper-based one to a group of 120 students to perform the design and verification process of a mandatory programming project. At a first stage, over 50% did considered using the system, but only 26 actually did some work with the system. Finally 11 students (A 19% of the interested users) completed their task using The On-line version is available with a restricted access. the system. Users must log in using a personal password stored in its We surveyed all students and found that those who have personal profile in the data base. liked the experience are in general those with problems to fit into a fixed schedule or those with free internet access. For these students it has been very helpful to work and deliver the result through a tele-learning environment. For 6 Experiences the rest, the main complain concerns internet access cost. The final environment produced can be either on-line or off-line by selecting an option at the compiler interface. The first one provides full user tracing of selected objects. The second one allows to create an environment to be delivered in a CD-ROM or to be installed in the student computer.

A first pilot experience has been carried out during the second semester at the Computer Science School of UNED University. We have set up two instantiated templates: A study guide (a consultive material) and a programming project (a working environment).

To overcome this problem, we have also developed an offline version of the material by mean of a new compiling option to the PALO compiler, thus providing a web material easy to suit into a CD-ROM, but providing full interactive functionality on demand (internet access is only

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Session 13a2 needed when submitting a result).1

7 Conclusions

metaphor. In Ana Paiva, Paul Brna, and John Self, editors, European Conference on Artificial Intelligence in Education, 1997. [5] M.D. Merril. The new component design theory: instructional design for courseware authoring. Journal of Instructional Science, 16:19–34, 1987.

Instructional templates provide a way to describe learning scenarios at a higher level than simple HTML editing. [6] Maglajlic S., Maurer H., and Scherbackov N. Separating structure and content, authoring educational PALO language allows to create web scenarios embedweb applications. In Proceedings of the ED-MEDIA ding complex paths,in order to carry out different learning & ED-TELECOM 98., pages 880–884, 1998. strategies over the same content material. Templates provide also a way to define reusable components, facilitating [7] E. Wenger. Artificial Intelligence and Tutoring Systhe authoring of learning material. tems: Computational and Cognitive approaches to the communication of knowledge. Morgan Kaufman Further work is in course to provide instructors with a viEd., 1987. sual creation tool of PALO documents, currently done using XEmacs editor.

8 Acknowledgements This work has been supported by the Spanish Ministery of Education through the Research Agency of Science and Technology.

References [1] Schwabe D. and G. Rossi. Object-oriented hypermedia design method. Comunications of the ACM., 8(8):45–46, 1995. [2] B. Manj´on, A. Valmayor, and A. Navarro. Improving world wide web educational uses promoting html/sgml content-based features. In G. Davis Ed. F. Verdejo, editor, The Virtual Campus: Trends for Higher Education and Training. Chapman & Hall, 1997. [3] Jos´e I. Mayorga, Felisa Verdejo, Miguel Rodr´ıguezArtacho, and Yolanda Calero. Domain modelling to support educational web-based authoring. In Proceedings of the TET 99 Congress, Norway, June 1999. [4] Jos´e Ignacio Mayorga and Felisa Verdejo. Authoring systems revisited: The software design cycle 1 This version of the learning material developed for this experience can be visited at http://sensei.ieec.uned.es/˜steed

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