I spent about two hours looking over the links on this site, going though them and trying out the interactive ones. Here are the ones I found to be interesting to me: The Sliding triangle, Linkages, The Planimeter, The Reuleaux and Inversion Geometry. I found this site to be fun and interesting at the same time, an interactive site that is educating and fun. I checked out about a dozen of the lessons and had fun trying out the interactive ones. I think this it a good site for young and old students and a good teaching site. The site explains the problems and shows you how to visualize the concept of it to, this is a good way to show what the out come is of the problem and how easy it is to grasp the concept of it. This is a very easy to use and is a very well designed site with descriptive, interesting visual effects, interactive perspective drawings and more. I find that using this types of visual effects not only help you to learn, it helps to make it more fun for the person learning or teaching.