Examples of simple educational modules that employ interactive techniques on the Web are presented and their potential use in fostering learning practices discussed. The first module, designed for the Unix platform, makes interactive use of HTML (Hypertext Mark-up Language) forms, where input and output data are processed using a CGI (Common Gateway Interface) program written in PERL (Practical Extraction and Report Language), a public domain script language. The module allows calculation of gravity values on the surface of the globe within a range of latitudes specified by the user. It may serve as a convenient starting point for teaching latitude variation of gravity fields related to the geometry and rotation of the Earth. The module also can easily be modified to address related problems of gravity fields related to the distribution of internal mass of the Earth. The second example, designed for the popular Windows platform, makes use of object-oriented programming capabilities of the Microsoft Visual Basic package blended with computational features of command line interface programs (such as Fortran). The module, which is a DHTML (Dynamic HTML) application, deals with the problem of determining thermal perturbations associated with past changes in climate. The main input data are the temperature records obtained in borehole logs. The GUI (Graphical User Interface) facilities of the Visual Basic package allow online graphic display of observational data and the model fits. The student is prompted to explore a set of model parameters that provide a best fit to observational data. The third example, written in Java, is platform-independent and illustrates the chaotic nature of the El Niño phenomenon. It provides a dynamic simulation of the position and temperature of the warm water pool on the surface of the Pacific Ocean responsible for large-scale climatic changes in the southern hemisphere. In this case input data include meteorological records and values of the parameters of the nonlinear differential equation that governs the process.
Trial experiments with these modules indicate that facilities for stimulating creative thinking can be set up more easily in Web-based systems than in those that rely on traditional teaching techniques. The implementation of such simple interactive modules can be carried out with relative ease by educational institutions in developing countries, as they minimize commitments in programming time and efforts by the existing staff. There is also greater flexibility in adapting them to frequent changes in the outline and scope of courses.