Geometer’s Sketchpad is a useful tool for visualizing euclidean constructs, as well as a multitude of other things. However, it is also expensive, with a new license running around $70, and renewals at $50.

Luckily, there is an open source version of the software called GeoGebra.

There are a number of links to help you get started with this free software:

http://www.geogebra.org/cms/en/download Here you can download the software for installation on your computer (this is how I use the program).

http://webspace.ship.edu/msrenault/tutorial/index.html Here, one may tour the GeoGebra software via a well put together tutorial.

That’ s all I have for the moment. A quick Google search for GeoGebra will pull up all kinds of reference materials

http://www.geogebra.org/webstart/geogebra.html

This link was supposed to open the latest version of the program,

in your web browser, but it didn’t work for me

The link requires that your internet browser has a java plugin, which you can obtain here:

http://java.com/en/

I don’t own a Mac but I think that they support Java even though you can’t get Flash. If anyone knows better, please let me know and I’ll look for a Mac friendly version of the website.

Here is what Wikipedia says about it’s origins:

GeoGebra is an interactive geometry, algebra, and calculus application, intended for teachers and students. Most parts of GeoGebra are free software. GeoGebra is written in Java and thus available for multiple platforms.

Its creator, Markus Hohenwarter, started the project in 2001 at the University of Salzburg, continuing it at Florida Atlantic University (2006–2008), Florida State University (2008–2009), and now at the University of Linz together with the help of open-source developers and translators all over the world. Currently, the lead developer of GeoGebra is Michael Borcherds, a secondary maths teacher.