The next issue of the Carnival of Mathematics, rounding up blog posts from the month of January, is now online at Storm Bear World.
The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.
In the Aperiodical’s Big Internet Math-Off 2019, Becky Warren posted an entry about Geogebra’s ‘reflect object in circle’ tool (it’s the second article in the post). I enjoyed playing with the tool and, after making a few colourful designs, it occurred to me that one of them would make a great cake for the MathsJam bake-off. It would only work if the curves were accurate; sadly this would be beyond my drawing abilities, and definitely beyond my piping abilities. But with some help from 3D printing I thought I might be able to manage it.
Here are the steps I used to transfer the design to a cake.
The next issue of the Carnival of Mathematics, rounding up blog posts from the months of November and December, is now online at Ganit Charcha.
The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.
#tmwyk is a Twitter hashtag which stands for some approximation of “Talking math(s) with your/young kids”. It is used to share mathematical interactions with children. It is also the subject of my MathsJam talk this weekend.
For me, I tend to use #tmwyk to share playful interactions with my son, following his interests and the mathematics that we find in the world around him. I’m not trying to teach anything in particular, nor am I trying to limit his interests to what might come up at school.
“Algebra?” said Madam Frout … “But that’s far too difficult for seven-year-olds.”
Thief of Time, Terry Pratchett.
“Yes but I didn’t tell them that, and so far they haven’t found out,” said Susan.
I’m grateful to Jemma Sherwood and Rob Low for reading an early draft of this and for their comments thereon. All opinions are, of course, my own.
This post is inspired by something that I see crop up now and again in discussions with other Maths teachers. It usually manifests itself as a rallying cry to use ≡ in place of = in identities and reserve = for equations. My standard response is to mutter something about identities being equations and leave it at that. But in the latest round, Jemma Sherwood challenged me, in the nicest possible way, to explain a bit further. This is that explanation.
Although I’m going to state my case here, I’m well aware that there are different opinions. In matters of opinion, such as this, agreement and disagreement is less important than that all sides think. So if what I write seems to you wrong, that’s fine so long as it makes you think about why you think that it is wrong.
At work we’ve got a 3D printer. In this series of posts I’ll share some of the designs I’ve made.
There are seven kinds of shape. There are three copies of each shape. The pieces like to group together in threes.
Can you arrange the pieces into seven groups of three so that for each possible pair of shapes, there is one group containing that pair?
Try to do it without paying attention to colours first, then try to rearrange the pieces so each group has a piece of each colour in it.
At work we’ve got a 3D printer. In this series of posts I’ll share some of the designs I’ve made.
This is something I’ve wanted to make for a long time: a literal sieve of Eratosthenes.
This is a collection of trays which stack on top of each other.
Each tray has a grid of holes, with some holes filled in. The tray with a “2” on it has every second hole filled in; the tray with a “3” has every third hole filled in; and so on.
When the trays are stacked together, the holes you can see through correspond to prime numbers: every other number is filled in on one of the trays.
I went through quite a few iterations of this design. The first version was a series of nesting trays. After printing it, I realised that you might want to put the trays in a different order. After that, I did a lot of fiddling with different ways of making the plates stack on top of each other. The final version has sticky-outy pegs at each corner, and corresponding holes on the other side. I had to add a fair bit of margin around the holes so the wall didn’t go wiggly when printed.
You can download .scad and .stl files for the prime number sieve at Thingiverse.