Overview

Flexagons are my favourite mathematical creation. Basically they are a sheet of paper folded and cut in a special way so that as well as having a front and a back you can fold them to reveal hidden sides. The most simplest flexagon is the tetra-flexagon meaning with 4 sides, this is the one we are going to make.

Here is a clip on how to use a flexagon.

Or you can download the clip here (0.9MB) You may need to download a quick time player as well. You can download either version here.

If you want to print out the flexagon click here. You have to print the flexagon on two sides of the same paper so make sure they are aligned.

Example

Front and Back

123-2346_IMG.JPG (406358 bytes) 123-2347_IMG.JPG (430942 bytes)

2 hidden sides

123-2348_IMG.JPG (428934 bytes) 123-2349_IMG.JPG (408060 bytes)

Instructions

With any rectangular piece of paper fold in quarters one way (usually the longest way) and thirds the other (usually the shortest way) so you get a grid of 12 rectangles. Number the squares off as follows (Keep these numbers small or use pencil so that you can draw a picture over them)

Front

flexagon front.JPG (17022 bytes) .

Back

flexagon back.GIF (10775 bytes)

	Turn on its front (withs the 1s face up) and cut on the dotted line. This forms a door fold this door back like so
	Fold the 3 on the left side ontop of the other 3 so you get a vertical line of 1s. Then fold the right hand side back between the 2s and 3s and then fold again between the 1s and 2s.so you should get 6 1s like so.

Stick a small piece of sellotape between the two middle ones (make sure it only goes on the middle two squares). On the back should be 6 2s. If you fold this back you get 6 3s. Fold this back again you should get 6 4s.