Greenhaus Education and Other "Effects"

I have been thinking and planning for my upcoming NCTM presentation on taking the hands-on, physical math manipulatives we use to help students learn and model mathematics to the virtual realm in order to provide  unlimited capabilities to explore and understand. It's something that I think is often thought of as an either or - either teachers use hands-on, physical models or they use virtual models, such as The Geometer's Sketchpad , and my thoughts are we should be using both. It's a way to help students see and understand the power of technology by exposing them to the limitations of the physical and then providing them the opportunity to see the capabilities to go beyond with technology. Some simple examples of what I mean: 1) Geoboards - students begin to explore polygons with geoboards, but are limited by the number of pegs on the geoboard, the number of rubber bands and the physical limitations of both (you can only stretch a rubber band so far before it snaps...