| Instructional system (IS)-system produced for the purpose of instruction or enhancing learning, is truly a blend of Computing and Education. On the one hand, it is educational oriented, it is surely a computational model of cognition on the other. With disciplines spanning from Educational Theory to Psychology to Knowledge Engineering to Programming, principles and techniques claimed related to IS are also diverse. Indeed the field is now at its crisis with disparate results and lack of rigour that people are getting disenchanted with it.;To remedy the situation, some unification that can set the diverse disciplines (together with the related principles and techniques) and works in place as well as laying a formidable foundation for the establishment and accumulation of results is required.;This thesis describes such a first endeavour towards the problem, namely Dimensional Extension (DE), a unifying framework for ISs. Basically DE is a computational-oriented framework such that the diverse disciplines, theories and principles related to the field of instructional system are allowed to be amalgamated and organized in a systematic manner such that cumulative progress in research is facilitated. In addition, analysis, synthesis and evaluation of previously seemed disparate works of the field can be done in a more coherent and rigorous fashion.;The unifying framework also provides the basis for the proper design of IS. This is demonstrated with the proposals of an engineering-based approach for IS authoring and a design language for IS namely the blueprinting approach and DLIS (a Design Language for IS) respectively. With their applicability illustrated via the design of an IS for elementary set theory.;In addition, the framework offers the basis for the formal addressing of ISs. This is demonstrated by two applications. One is on the proposal of a formal scheme for taxonomizing instructional systems such that different systems' complexities can be objectively analysed and compared. With ISs as instantiations of the scheme (parameters), the evolution of ISs following computing advent is also traced. The other application is on the formal evaluation of IS. With a formal framework described, the computational complexity of IS effectiveness is first evaluated. The intractability of the pedagogic modelling problem is also proved.;Finally, the thesis summarizes what have been achieved by putting forth a philosophy for approaching IS. The limitations, extensions and scope for further research related to current work are then discussed. |
