How to make a square Flexagon

Last month I posted a group of photographs documenting flexagons made by fifth grade students. These structures are best seen (and held) to be understood, but, basically, they are a paper toy whose folds, when articulated, reveal hidden surfaces.  Got that ? If not, check out Forest of Flexagons.  To make a larger copy of the directions shown above here’s the PDF for Flexagon Squared

There are other shapes for flexagon. I also make ones that  are hexagon-flexagons, which I like like because its structure can  be decorated to mimic  fractals.  But that’s another story.