Some people folded paper airplanes in class, some people made paper footballs, and some people end up discovering a whole new field of geometry. Because if you fold a strip of paper in just the right way, you can construct an object that makes a Möbius strip look flat in comparison, with more sides than you can imagine.
From Khan Academy‘s fast-talking “mathemusician”, Vi Hart, here’s an inside out and upside down tour of one of the most curious constructions around – the flexagon, and more specifically, the hexaflexagon:
More info on these structures is available at Flexagon.net, and if you’ve never really liked math, but want to learn more from a fun and witty instructor, check out some of the other offerings from Hart at Khan Academy. You’ll be educated, amused, and get a new perspective on “recreational math”.