Student module Teacher module Domain knowledge module User interface module Figure 1. Typical ITS Architecture Abstract – Asynchronous distance education delivery systems do not require real-time student-human teacher interaction thus enabling students to use tutoring resources anytime and anywhere. Among various possibilities for implementing asynchronous distance education delivery computer supported ones are nowadays the most popular. Categories thereof are intelligent tutoring systems that are used for supporting and improving the process of learning and teaching in arbitrary domain knowledge. In such education models the role of human teacher is replaced with a computer tutor basically consisting of a domain knowledge base as well as of both a student module with an appropriate student model and a teacher strategy guiding the learning and teaching process. The paper describes an authoring shell – Distributed Tutor- Expert System (DTEx-Sys) – developed for asynchronous distance education purposes, as a secondary knowledge source for teachers and their students in secondary and primary schools. Index Terms – asynchronous distance education, authoring shells, intelligent tutoring systems. I. INTRODUCTION The growing popularity and ease of access to the World Wide Web (WWW) stimulates present day interest in systems for self-learning in general and distance learning (DL) in particular. The Web provides itself as an outstanding delivery medium, thus acting as both a provider of content and of subject matter. On the other hand HTML technology allows and easy way to deliver all kinds of text, graphics, sound and video offer. It is claimed that the Web represents a well-chosen technology for implementing asynchronous distant education delivery systems. Such systems do not require real-time student/human teacher interaction hence enabling students to use tutoring resources anytime and anywhere. Moreover, students within asynchronous group learning environments do not need to manage their schedules. Learning networks based on asynchronous communication offer unique opportunities for active participation. Unlike the traditional classroom, students within on-line courses have access to the airtime they want or need, enabling every one of them to have a voice. Asynchronicity provides each Marko Rosić and Slavomir Stankov are with the Faculty of Natural Sciences, Mathematics and Education, University of Split, HR-21000 Split, Croatia (e-mail: marko.rosic{stankov}@pmfst.hr). Vlado Glavinić is with the Faculty of Electrical Engineering and Computing, University of Zagreb, HR-10000 Zagreb, Croatia (e-mail: vlado.glavinic@fer.hr). student the time to reflect, formulate ideas and compose responses thoughtfully, hence enabling the elevation of the quality of student interaction and participation. Among various possibilities for implementing asynchronous distance education delivery computer supported ones are nowadays the most popular. A category thereof are intelligent tutoring systems (ITS) that are used for supporting and improving the process of learning and teaching in arbitrary domain knowledge. In such education models the role of human teacher is replaced with a computer tutor, basically consisting of a domain knowledge base as well as of both a student module with an appropriate student model and a teacher strategy guiding the learning and teaching process [1]. An ITS takes into consideration the knowledge about what to teach (subject matter – domain knowledge), the way to teach (pedagogical strategy – teacher), as well as the relevant information about the student being taught (student). As shown in Figure 1, there are four main interconnected modules of an intelligent tutoring system: (i) domain knowledge module with the domain knowledge base, (ii) teacher module for guiding the teaching and learning process, (iii) student module with information that is specific to each individual student, and a (iv) suitable user interface module enabling interaction among student, teacher and domain knowledge [1,2]. Teaching and learning are expressed by a four-phase functional cycle: (1) didactics, (2) perception, (3) diagnostic and evaluation and (4) help and remediation [3]. This process is a self-adaptable one and is performed according to the assumed pre-knowledge, capabilities and students' behavior. Intelligent Tutoring Systems for Asynchronous Distance Education Marko Rosić, Slavomir Stankov, and Vlado Glavinić, Member, IEEE