The picture for today’s door of the CS4FN Christmas Computing Advent Calendar is a snowflake and, inspired by its six-sides, this post is celebrating the similarly six-sided (and six-faced) hexahexaflexagon.
A hexahexaflexagon is a strip of paper cleverly folded to hide and then reveal six hexagonal faces within it. You pinch and flex them to reveal another face, as shown in the video below. It’s effectively a Möbius strip.
The name references a hexagonal shape which is flexed to show a new face (‘flexagon’) and the hexa-hexa bit just means each face has six sides and there are six faces.
Flexagons were discovered in the late 1930s by a British maths student (Arthur Stone) who’d arrived at Princeton University with a binder / folder from home and discovered that American paper was too large to fit in. He cut off the excess strips and ‘doodled’ with them by folding them into different shapes, then involving his classmates in developing them.
There are lots of ways to make them but we’ve created some templates to help. You can print our hexahexaflexagons or make and decorate your own from scratch. Ours depict Father Christmas looking for the six presents he’s lost among the different faces but there’s a blank template if you’d like to design your own.
Of course there’s some computer science and maths behind these too – we have a free PDF booklet which you can download from the link below, called Computational Thinking: HexaHexaFlexagon Automata.
Previous Advent Calendar posts
CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)
CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)
CS4FN Advent – Day 11: the proof of the pudding… mathematical proof (11 December 2021)
CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors – (12 December 2021)