Making at Mathsjam

by Julia Collins

Tuesday 21st June was a notable date. Not only was it the winter solstice, the shortest day of the year, but it was also a full moon, the first to fall on a winter solstice since 1967. It was also the second-to-last Tuesday of the month, which meant it was MathsJam night! Now, the full moon/solstice combo won't be happening again until 2062, but MathsJams happen all over the world at 7pm on the second to last Tuesday of each month, so if you missed the one this week then make sure you find your local 'Jam next month!

MathsJam is a friendly place for people to geek out about maths, is open to anybody, and is usually held in a pub or cafe. At the Auckland MathsJam this week we took the opportunity to play about with some maths craft ideas to see what people thought of them.

I set to work making an origami dodecahedron using post-it notes, while fellow festival-organiser and mathematician Phil used his post-it notes to make a beautiful 11-sided shape. Sadly Phil cannot remember the method he used to build his shape, so it will be a challenge to our readers to recreate this, but the instructions for the dodecahedron are well-documented online.

There are actually a few different ways to create this 12-sided shape from origami, and the one I use is described best in this Youtube video by James Grime. There are also written instructions on the Instructables website. Post-it notes work particularly well because the sticky bits help to hold the shape together as you're building it. A fun exercise is to calculate how many pieces of paper you'll need before you start! Can you figure it out?

You can also build a dodecahedron using A4 or A5 sized paper. In this method, you create the faces of the shape rather than the edges.  

The dodecahedron is a Platonic solid, meaning that all its sides have the same shape, all the edges have the same length, and all the angles are the same. There are only 4 other such shapes: the tetrahedron (made of 4 triangles), the cube (made of 6 squares), the octahedron (made of 8 triangles) and the icosahedron (made of 20 triangles). You can make some of these other symmetric shapes using origami sonobe modules, or yet another origami method.

At MathsJam Phil made another really cool thing, which is a pop-out fractal tree. For this you will need a pair of scissors and some paper. If you like you can mount it on card afterwards to make a unique greetings card for a friend. Follow the instructions on this website and see how fractal you can make your tree!

We're excited to have all these activities at our Maths Craft Festival and to see how creative people will get with all these basic origami and paper ideas.

You can follow MathsJam on Twitter to find out what other geeky things people were doing around the world on this special full moon solstice.