Geometer’s Sketchpad is a 2D program. As such one would think that it does not do 3D well. But we have worked out ways to make this a great 3D program.

The Paideia 3D and 4D technique. This was mostly worked out by Adam Konner, Corey Kasten, Andrew Berry, and Katharine Pierce.

The basis of the technique is that one makes certain parts of a construction rigid and other parts flexible. In sketchpad objects that are constructed are considered rigid in that constructed points are constrained to do as their construction requires. For example a constructed square will always be a square. A square drawn freehand will be limp in that each part can be moved independenly. The secret to effective 3 and 4 D objects is to make some parts of them rigid and some not. A very nice way to create a cube is to use rigid squares connected non-rigidly. In this way one can grab a square and pull the cube apart and see details therein.