This package is written my Michael Hvidsten, who wrote a PhD for Philippe Tondeur in our Department several decades ago. It is somewhere between Jackiew's "Geometer's Sketchpad" and Richter-Gebert's "Cinderella" in sophistication. It is very easy to learn, and its GUI is based on sound geometrical principles, which one needs to think about when using it. It also is minimalist, in that it does just enough for each of its topics to be useful in conjunction with a college geometry course. It "does" the hyperbolic plane only in the Poincare model, because the Beltrami-Klein model can be constructed with "ruler and compass" in the Euclidean plane. On the other hand, this is the only package I know that also has functionality in Turtle geometry (yes, it has a hyperbolic turtle), and in the geometry of fractals, Lindenmayer systems and other fashionable esoterica.
GF 26oct02

We have experienced some technical difficulties using the online help system included with Geometry Explorer, presumably because of a bug in the Java browser used to view the help files. We have circumvented this problem by transferring the help files to our website so they can be viewed with any web browser. The help files can be accessed here.
WH 11nov02

click on the image below to go to the Geometry Explorer website.