I spent a short time looking at your material here on basic geometry: parallel lines and angles to be more specific, and I was impressed by it. The lessons taught in it are clear and consise, well-organized, easy to understand, and very practical to students learning this type of material. I'm going to eventually teach mathematics when I graduate and would definitely consider using this or a site similar to it to teach my students about lines and angles. That is probably the age of students that i will be teaching as well. I think the material is very easy to use and the students may even learn more because of the fact that it is on the computer and they can move and manipulate the lines and angles and come up with their own ideas and theories about the concepts at hand.