Penrose Tiles without Matching のコピー
This was a preliminary sketch for the tiling with matching alterations, but some people prefer the unaltered tiles that allow more incorrect placements... plus there is a beauty to the simplicity, I think.
The subsequent sketch is at http://www.geogebratube.org/material/show/id/35252, and it has several links for learning more about Penrose tiles.
More GeoGebra at mathhombre.blogspot.com