Abstract

Efficient Development of Multimedia Applets for Elearning

Applets are a very useful multimedia teaching aid offering interactive visualizations, explorations and various types of exercises. The high degree of interaction is a main point for using applets in distant education. There used to be a lot of technical problems in using Java applets but nowadays almost every browser supports Java and the high performance of common personal computers makes even more complex tasks possible. Unfortunately, the development of high quality applets is an intensive and expensive work. There are lots of conditions and aspects to consider. Especially in the context of elearning several additional didactical factors (e.g. how to represent the content, the use of hints, the grade of interaction, the choice of colours) have to be taken into account. So one has to deal which each applet individually and there is no way in sight to produce applets off the peg. A possibility to make applet development more rewarding is to produce applets (or parts of applets), which are easy to re-use. In this article we discuss some possibilities to increase the efficiency of applet development in the elearning area. Important aspects are:

• Re-using parts of the source code. With the aim to achieve high re-usability of most of the source code we exploit the capabilities of object oriented programming languages like Java. Moreover, Java allows for a flexible construction of graphical user interfaces (GUI). Thus for each task we implement a subject-specific 'base' class and produce various applets by combining the 'base' class with appropriate 'tool' classes. The 'tool' classes are used to implement frequently required functions such as navigation, input forms or output of comments. So in most cases adding a few lines of individual source code is enough to produce applets for explorations,
• Using an applet in several learning contexts. We show an easy way to influence the behaviour of an applet using starting values. In particular this is quite useful for applets with mathematical or technical content. One can offer the same applet with fixed values or random values or one can enable the students to choose values on their own. Hence there are even more possibilities for the use of one single applet, e.g. it can be used
  • with fixed values as an example in a lecture text,
  • with random selection to provide an inexhaustible amount of exercise
  • with an input form in an exploration area.
• Using applets in different courses. To encourage more teachers to integrate external materials in their lectures our applets meet special demands: based on the sharable content object reference model (SCORM) they are independent of the special context and adaptable to individual preferences (i.e. colours, fonts, identifier, terminology). Hence they can easily be used as 'bricks' in different courses by different teachers.