Hello all
A hexahexaflexagon is a strip of paper folded first into equilateral triangles and then in such a way that it forms a hexagonal flat disc with two visible sides. But... there are four faces hidden within it which are revealed by bending and flexing to open it up. It's quite a fun fidget toy and a small challenge to find all of the six sides. It's basically a fancy triangular Möbius strip.
I've created some free printable templates (and instructions if you don't have a printer). They're a nice size if made from A4 paper as they're easy to colour in. Mine have designs already printed on them or you can use the blank hexahexaflexagon pattern (called a 'net') to make your own.
cs4fn.blog/2021/12/12/cs4fn-advent-calendar-hexahexaflexagons/
Note that it's a strip of triangles so when colouring them in it's helpful to follow the instructions if you want each of the six faces to have the same colour triangles. Folding the strip up puts different triangles next to each other.
The name hexahexaflexagon comes from hexagon - a six-sided shape, but it's hexa-hexa-flexagon because there are also six faces. Flexagon because it's a flexible polygon shape. Discovered by Arthur Stone, popularised by Martin Gardner.
For maths or computing minded kids and grandkids there's also a free booklet that talks about graphs / maps / nodes and finite state machines. But they're also fun things to just colour in and play with and wonder where the hidden faces are.
This is part of the advent calendar I've been making for work (with a post every day about some aspect of computer science, tenuously linked to a festive image!) cs4fn.blog/cs4fn-christmas-computing-advent-calendar/
Hope you enjoy them :)
Jo