**Description**

Hexaflexagons
are gadgets invented by the topologist
Arthur H. Stone and
popularized in
Martin Gardner's Scientific American Column. The article appears
in his book *Mathematical Puzzles and Diversions*.

This presentation is more of a workshop than a talk. First, we construct hexaflexagons with three faces and with six faces and learn how to flex them. In playing with the hexahexaflexagon, novices are quickly struck by the difficulty of locating all six faces. We then have a discussion of how to resolve this problem, and if a solution is reached, we discuss how to construct hexaflexagons with different numbers of faces and different internal structures.

**Level**

Elementary.

You need to be able to write numbers, to crease a sheet of paper along a marked line, to apply adhesive, and to follow instructions. That's it.

If the audience has higher mathematical capability, we cover more ground accordingly.

**Mechanics**

I use an overhead projector and, if available, a blackboard.
I supply the paper strips for folding and ask that the audience
bring pencils. I also bring glue and tape, but
local sources of more glue and/or tape help speed the flexagon
assembly process.

**Appearances**

- Interterm Course (series of three workshops), Amherst College, January 1991
- Harvard University Graduate Student Seminar, October 1994
- Math Circle, Boston, May 1998
- Radical Pi, Ohio State University, May 2002
- Mathematics and Computer Science Club, St. Mary’s College of Maryland, September 2005

Printed Flier for Radical Pi Talk