In designing and writing an educational applet, we need to aim at certain specific design goals. The most important thing is the educational content . Educational content may be the concepts and principles to teach/learn in this applet. The content must be such that the users can learn concepts and principles in an intuitive manner from the visualized processes. Once the important scientific concepts and principles to teach and thus the basic content of the applet is determined, the programmer's effort should be concentrated on how the various components in the content are laid out through various GUI Components and Containers and how the users interact with this applet to learn these principles effectively, without distraction.
The use and layout of graphical user interface (GUI) is important. It should let the students focus on the meaning of scientific principles . The complexity (or simplicity) of layout, background color, and the kinds of interface components are all important in influencing how well the user can focus on the principles without distraction.
More to follow.
Several useful GUI components and their example codes