Video of a hexaflexagon being folded.
My father, Roy A. Gallant, introduced me to hexaflexagons when I was a child after he saw an article in Scientific American. The hexaflexagons shown on this page are made from strips of paper folded into 18 equilateral triangles. They're magical in that they have 6 faces, 2 of which appear far less often than the other faces in the course of repeated folding. They're mildly challenging to make but lots of fun. My son Max, age 7 at the time of this writing, and I have perfected a way to make many at the same time.
Video of a hexaflexagon being folded.
One side
Another side
A file folder all marked up ready to cut into strips of triangles
Writing numbers on the big sheet
Ready to color