the above example is too simple, although, we can imagine a more complex one such as as geometry applet extension wich allows you to define the carachteristics of a given geometrical construction and then the user can interact with it.
Imagine a geom. construction with some of the lengths and angles undetermined (so, denoted by literals). The user (maybe a student at wikiversity) could then click and drag vertices in order to see how the whole construction conforms to the lenght and angle variations. This would provide greater flexibility and understanding than what we can get today from geometry books and blackboards (with their static images of these geom. constructions).
Juca