Dynamic geometry is a piece of software for exploring interactive math constructions directly on your screen. It lets you create any ruler-and-compass constructions using your mouse or stylus. It also allows you to play and experiment with the drawing using drag-and-drop (this is not possible on paper).
The points in the drawing are actually draggable - as you drag a point, the triangle will change with the rest of the construction. You can create hyperlinked and commented interactive documents:
and live measurements:
If you're interested (or you have kids who currently study geometry), you can download DG 1.0 from my website: dg.osenkov.com. The software is free and no setup is necessary, just unzip the archive to any folder and run Geometry.exe. Please let me know if you have any questions or feedback, I'd be happy to help.
A bit of history
For the curious ones, DG is a piece of software I wrote in 1999-2002 when I was working for the Kharkiv pedagogical university in Ukraine. A great team of teachers, methodologists and mathematicians worked on this software package, which includes more than 250 interactive drawings to support the school geometry course. I was the only programmer on the project with about 5 PMs and 5 testers :) It is great to know that DG is still being used in many ukrainian schools in geometry lessons, after we shipped the software in summer 2002. The idea of dynamic geometry dates back to 1980's, there are many dynamic geometry programs, so I'm not saying we invented anything new. But we implemented DG to specifically suit the needs of ukrainian teachers and students, and it also turned out to be a pretty good piece of software for everyone else to use. So I decided I'd blog about it, so maybe it could be of some use to someone.
Although it has been more than 5 years after we shipped DG, I still sometimes receive feedback from teachers. I'm always happy to see anyone using DG, because I put a lot of soul and effort into this project at that time. Thanks to this project, I grew from being a geeky teenager that I was in 1999 into an experienced developer who shipped and deployed working and tested software in 2002 that still works in 2007 :) I'm very thankful to our project leader, Sergey Rakov, who I also respectfully consider my personal Teacher.