I've written quite a bit about using Linux to help educate people. In the past, I've discussed using Linux to teach astronomy, programming and computer logic design. So today, I'm writing about using the KDE Interactive Geometry (Kig) program to teach mathematics. Kig allows you to use various tools to diagram and demonstrate different mathematical concepts. With Kig, you can draw points, lines, line segments, half lines, vectors, circles and various other conic sections. When Kig refers to a “half line”, it means what I was taught was a ray—essentially a line with one endpoint. Drawing hyperbolic curves on the computer sure beats getting dry-erase marker all over yourself or sneezing because of chalk dust.