As educators in a university context, a substantial amount of our time is taken up with the activity of teaching. We know how the teaching activity varies with factors such as class size (e.g., 20 versus 400 students), instruction type (e.g., lectures, tutorials, laboratory supervision), the nature of the subject (e.g., conceptual, problem solving, design oriented) and so on, and we discharge our teaching responsibility as best we can in whatever teaching situation we find ourselves.

All too often, however, the teaching responsibility so swamps us that we forget to think beyond teaching. In this article, I direct attention to the flip side of our teaching activityto focus attention on students' learning insteadand to share some viewpoints concerning learning and epistemology. I shall also describe two computer-based learning environments that we have been developing in the Department of Information Systems and Computer Science as part of our efforts to devise useful tools to support students' learning.

Consider the typical lecture session that occurs in the university. The lecturer arrives. He delivers his lecture using transparencies or presentation slides. He leaves. The amount of interaction that occurs between lecturer and students is usually minimal, especially when the student enrolment in a course is high. As educators, it behoves us to consider this question: how much does a typical student learn from attending a lecture? My experience tells me that the answer is "not a lot."

Learning, especially learning with understanding, can only be attained at a much higher cost in terms of a student's time and effort. Lectures provide an effective means for disseminating domain information, but listening to a lecture goes but a short distance along the road to learning with understanding. Why is this so?

Intensional vs. extensional meaning

To better appreciate what it takes to learn meaningfully, we need to turn to epistemology and consider the epistemic dimension of learning. We need to have some appreciation of what it means to know and how we come to know. Hayakawa and Hayakawa (1990), in their book Language in Thought and Action, draw an important distinction between intensional and extensional meaning. Briefly, the intensional meaning of a word or expression is that which is connoted in a person's head whenever the meaning is expressed using other words; it is based on natural language.

On the other hand, the extensional meaning of an utterance is that to which the utterance points (or refers to) in the physical world; it is based on our experience in the real world. Seen in this light, the quest for meaning and meaningfulness in human learning can never be attained if we operate entirely at the level of intensional meaning. Thus, I would never succeed in learning German (or any other natural language) if all I have to learn the language from is a German­German dictionary. There is no way to bootstrap the semantics of the words used in such a situation. Indeed, one might go further and assert that dictionaries don't contain meaning. They can't. At a literal level, all that dictionaries contain is carbon on paper. Meaning making through interpretation of the symbolic forms perceived in a dictionary is an entirely human cognitive activity. Words don't have meaning of themselves; rather, we give them meaning.

Following from the above, it should be evident that experiential grounding is a prerequisite for meaningful learning. Experience provides the extensional grounding for words and concepts, thus imbuing them with rich semantics. Once a core set of concepts is grounded, learning and reasoning can begin to operate on the intensional plane. The weakness of the lecture instructional method arises out of the teaching context (typically, a lecture theatre) that provides little support for experiential grounding. Hence, students find that new terms and concepts introduced during a lecture have, at best, a fuzzy meaning, until such time that they begin to engage in active forms of learning (e.g., attempting tutorial questions, running a lab experiment or writing a computer program).

The viewpoint propounded above is consonant with what is known from the field of neurobiology (see, for example, Gerald Edelman's book Bright Air, Brilliant Fire: On the Matter of the Mind). Changes to human memory that arise out of learning experiences are realized neurally by synaptic modifications in the cerebellum, basal ganglia and hippocampus. These modifications occur over longer time scales and are related directly to human experience. Furthermore, it is expedient to recognize that the brain stem and limbic system also play an important role in learning. They manifest themselves in the affective and emotive dimensions of learning and impact upon the memorableness of the things we learn. It is refreshing, therefore, to see increasing importance being placed on project-based learning within the university because project-based learning provides a more conducive context for meaningful and experientially grounded learning. There is ample evidence for this claim. In a third-year project that I recently evaluated, the students wrote: "This project has given us a golden opportunity to put what [we] were taught in NUS to good practice and experience the gap between theoretical knowledge and practical application in the actual execution of building a system."

The social construction of knowledge

Assuming the grounding of extensional meaning through experience, meaning construction can be facilitated further through language-based discourse. From a social constructivist viewpoint, the main task of intelligent human effort is to make stability of meaning prevail over the instability of unfolding real-world events. Knowledge and knowing result from processes of social interchange and interaction with the environment. Knowledge acquisition does not entail absorbing truth, as defined by some outside criteria, into one's mind. Rather, it is the direct consequence of social interaction.

The goal of instruction, then, is to nurture the ongoing processes by which learners ordinarily come to understand the world in which they live. The role of teaching shifts from seeking to maximize the communication of fixed content or skills to one in which students are led to construct interpretations, appreciate multiple perspectives, develop and defend their own positions while recognizing the views of others, and to become aware of and be able to manipulate the social process of knowledge construction itself. These processes of human learning inherently entail social couplings based in language. Human learning is, in a very real sense, human languaging: the exchange of conversation and dialog. Individuals come to see the world by representing it socially through conventional means such as language.

The social constructivist perspective on knowledge construction accords well with our understanding of how human knowledge is created. Scientific knowledge production, made evident in conference presentations, panel discussions, journal publications and scholarly critique and rebuttal, effectively encapsulates the process of socially grounded knowledge construction. We need to engage students in a similar learning process. As part of this process, students are naturally encouraged to seek out information, filter and evaluate it, apply information to support a stance and critique, defend and rebut points of view. These activities foster the development of critical and independent thinking skills. They also help to inculcate an attitude of life long learning.

Again, it is refreshing to note that the university now de-emphasizes rote learning and emphasizes critical and independent thinking. How can we help facilitate learning of the kind espoused here with the aid of computer-based technologies?

Using technology to support learning

In this section of the article, I outline two computer-based learning environments that we have developed in the Learning Environments and Learning Science Laboratory in the Department of Information Systems and Computer Science. The design of both learning environments is driven by the viewpoints expounded above.

Mind Bridges/Web is a learning environment designed to support media-rich student co-articulations as part of a collaborative knowledge building process. The environment allows students to express their thoughts on any subject matter in a threaded form of discussion. Students can import text, pictures, sounds and digital movies in the creation of their messages. They can also directly record sounds and digital movies into their messages. The multimedia elements enhance the representational power of the ideas that can be expressed. All multimedia elements play back in situ.

Mind Bridges/Web: An web-based platform for student dialog and multisensory learning

Mind Bridges/Web runs as a web-based application. Communication between students takes place in an asynchronous fashion. In addition to browsing and responding to threaded discussions, students can also perform keyword-based search to find relevant messages. The Mind Bridges/Web snapshot (shown above) illustrates what it is like to read a multimedia message incorporating a digital movie, text and a picture using the Mind Bridges/Web client.

The second project, VRoom, is a learning environment for highly socialized meaning con-struction and knowledge building. Unlike Mind Bridges/Web, VRoom is a real-time,synchronous system where students navigate in a virtual world, meet other people and discuss ideas with them. VRoom, an acronym for Virtual Reality Object-Oriented MUD, is a system that integrates virtual reality technology with object-oriented MUDs (also known as MOOs). Unlike traditional text-based MOOs, however, world building is not an important element in VRoom. Rather, the aim is to support a highly socialized form of learning interaction between participants in the virtual world.

The VRoom snapshot (shown above) shows how participants in the virtual world, represented by avatars, can roam the virtual world and engage in learning conversations with other participants. The virtual world is full of life. In the background is a digital movie on a wall that can be played, observed and commented upon by the two human-like avatars shown. In addition, the virtual world supports animation (the rotating zebra in the cage) as well as sound (when approached and clicked, the monkey will animate and speak at the same time).

Conclusion

It is hoped that readers will be able to appreciate how systems like Mind Bridges/Web can be deployed to support media-rich knowledge construction and, in the process, develop students' critical and independent thinking skills. Learning environments like VRoom, on the other hand, can lead to deeply engaging forms of (physically) remote yet highly productive collaborative learning. In the not-too-distant future, we hope to deploy these systems for student use within the university.

I have attempted, in this article, to share certain epistemologically grounded viewpoints concerning learning and to illustrate how, based on these viewpoints, we have developed learning environments to support students' learning. It should be noted that these systems are oriented toward knowledge construction and to acquiring conceptual understanding. They do not, for example, foster skill acquisition. Experiential grounding, through the pursuance of projects, for example, must still take place outside of these systems as a complement to intensional knowledge building.