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Bellhop
Very clever, Brian! You spread it out over ten pages so that you could get ten ...
kjdsfkjdshfkdshfvc
I know I'm getting old, but when I learned drafting, that pointy thing was ...
Using HexaFlexagons to pass secret messages
Brian Bailey
10/2/2012 6:36 PM EDT
A facebook posting reminded me of something I used a lot when I was in school and had forgotten all about them. We used them for sending secret messages to each other. I am talking about hexaflexagon. Technically, a flexagon is a flat model, constructed by folding strips of paper that can be flexed or folded in certain ways to reveal faces besides the two that were originally on the back and front. Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix is added to the name to indicate the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon. There are many of these and many ways to make them, but I thought I would show you the one that I know which is a trihexaflexagon.
What you will need. A piece of paper, scissors, glue and a protractor. (Sorry the glue is missing in the picture. You can use a glue stick or I used Elmers.

Next: Marking an edge


Geoff_J
10/4/2012 12:59 PM EDT
Or you could watch this :
http://www.youtube.com/watch?v=VIVIegSt81k
This video is based on, and in honor of, Martin Gardner's first Mathematical Games column from 1956, "Hexaflexagons," which can be found here: http://maa.org/pubs/focus/Gardner_Hexaflexagons12_1956.pdf
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ccalvin
10/8/2012 3:04 PM EDT
I remember reading about Flexigons in SciAm while in Jr. High School. And colored the faces, concealed messages, etc. The mma.org link is interesting as Bryant Tuckerman, Richard Feynman, and John Tukey are mentioned on page 3 as some who worked with flexigons.
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alaki
10/5/2012 12:56 PM EDT
Seems someone running out of ideas! :)
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BrianBailey
10/9/2012 12:55 PM EDT
We all need distractions from our working life at times and some of these things from our past are fun.
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kjdsfkjdshfkdshfvc
10/9/2012 1:37 PM EDT
I know I'm getting old, but when I learned drafting, that pointy thing was called a compass, not a protractor.
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Bellhop
10/9/2012 4:02 PM EDT
Very clever, Brian! You spread it out over ten pages so that you could get ten page-view clicks from each reader!
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