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Chocolate Flying Machines

Toblerones are a very Christmassy thing, and I got a drone last week. The Tello drone is controllable from Scratch… and Makey Makey. I’ve been looking for a way to combine it with Makey. I bring you Tobledrone – the edible drone controller.

A Makey Makey Labz guide is in the works.

Countdown 2019

Quick post about numbers. Back in 2017, @aap03102 asked me if I could write a program to insert basic operators into a string of numbers, e.g.

1 + 2 – 3 + 4 ÷ 5 …

We were trying to find 10,958, which is the only ‘gap’ between 0 and 11111 if worked out this way (work of Inder Taneja - see this link). The closest we got was 1.2 + ((3/4) ^ (5 – (6 x 7 x (8/9))) = 10958.052439016.

I remembered this today when I saw 2019 countdowns, so started up the Discombobulator and Number Tokenizer (couldn’t think of a good name) and found this – plus 1930 other results (there’s a bit of overlap with redundant brackets that I couldn’t be bothered filtering out).


Anyway, download link for the program is here: discombobulator

Source code (Visual Studio project): discombob_source

Makey Makey Featured Guide: Walk-on Maze

I’ve always felt interactive programmable floor mazes were just too… static. So why not make one you can take with you?! Actually, I just use multiple classrooms, so it was easiest to make a roll-up portable version that could be moved between rooms when we were working on it.

I’m pretty chuffed that my maze remix is featured and has been taken as the #CSEdWeek Hour of Code Challenge Day 3 by Makey Makey – and they made blog post about it.


This is a take on the Makey Makey Journey, whereby two people walk along a conductive path – holding hands – to control a computer game. We made our own version with tinfoil tape (becoming one of my favourites) and plastic outdoor sheeting.


One path is wired to the Earth terminal, and the other to Space. The connection was a bit ropey at first, but we managed to find where it was dropping off and added some booster wires.

We used Scratch to make a circus game with a tightrope-walker and big top music. The featured guide is on Labz and Twitter, and explains it best. This includes a (hopefully funny) video.

Now, I’m away to frame my maze and stick it on a (large) wall in my parents’ house.

Maths Week: Binary Game (update)

Video and full instructions for the Makey Makey binary game.

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Maths week: Makey Makey binary game

Who hasn’t wanted a Makey Makey binary number dance mat? This is a post for Maths Week Scotland 2018.

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Giant micro:bit

Inspired by the recent giant Makey Makey (I want one of those too!) I said I’d love a giant micro:bit I could demo from the front of the class. My dad – an engineer – said he could make one, but I didn’t expect this sort of detail! It’s great to point out the connectors, where to find the processor and sensors on the back, where the Bluetooth antenna’s hidden, etc. It’s a prop, a talking point. It’s 10x scale, as you can see from the tiny (real) micro:bit sitting on top of it. How cool is this?!

Giant microbit

Video: Makey Makey slide mover

20180722_130151Ever been frustrated when your slide clicker runs out of batteries? Me too! My Code Club kids, and Pi-Wire pal Chris, have a ‘practical’ solution: use a piano pedal!

There were two versions: the first was ok, but had some flaws. As later figured out, it was a bit unreliable. I was so impressed that the kids developed ideas for version 2, improving it a lot! With a bit of tweaking, the second version was perfect – and all it took was some play doh and a bit of rewiring. Click below to see how we did it…

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2018 Update

This hasn’t been updated in ages, but…

As of July 2018, I’m a secondary computing science teacher (“probationer” in Scotland, newly-qualified teacher, or NQT). I’ll mostly be keeping this site on as an archive, but I tweet more often as @mrmckaycomp. I did the Strathclyde PGDE and worked in two great placement schools. I’ll now be taking up an NQT post in another (I’m not telling you which) secondary school.

Pi-Wire stays (it hasn’t been updated in ages either) – and we’re now both teachers!

My Google Scholar page is here too, with a list of publications/citations.

HCI 2013 publication – cognitive models

I have a paper coming up at BCS HCI 2013 (September 11-13th, London), “Predictive Modelling for HCI Problems in Novice Program Editors” (Fraser McKay and Michael Kölling). It’s a predictive human performance modelling approach to learner programmer tools, carried out with CogTool. Second author is my PhD supervisor. From the abstract:

We extend previous cognitive modelling work to four new programming systems, with results contributing to the development of a new novice programming editor. Results of a previous paper, which quantified differences in certain visual languages, and feedback we had regarding interest in the work, suggested that there may be more systems to which the technique could be applied. This short paper reports on a second series of models, discusses their strengths and weaknesses, and draws comparisons to the first. This matters because we believe “bottlenecks” in interaction design to be an issue in some beginner languages – painfully slow interactions may not always be noticeable at first, but start to become intrusive as the programs grow larger. Conversely, text-based languages are generally less viscous, but often use difficult symbols and terminology, and can be highly error-prone. Based on the models presented here, we propose some simple design choices that appear to make a useful and substantive difference to the editing problems discussed.

This is a short paper, that ties up the loose ends of a previous HCI paper.

EDIT 12/09/13: I’ve posted a link to my copy of the PDF, and it’s also in open-access on the KAR (my university’s institutional repository). ACM and BCS links will (presumably) follow once available.

How to draw pi…

3141 digits with stampI’m possibly the least mathematically-minded programmer I know, but a maths-teacher friend recently prompted me to throw together an app we’ve called Pi-Wire. It started with the mathematical artwork of Cristian Ilies Vasile. To quote Visual news,

First Cristian Ilies Vasile had the idea of connecting each digit of π to its successive digit with links to the position of the numerically corresponding segments. Martin Krzywinski added to Vasile’s visualization…

The effect’s pretty impressive (check out the links). It distributes the digits 0-9 around the edge of a circle, and visualises the order in which they appear in π (or another constant). So, for the digits 3.14159, it draws connections from:

3 → 1, 1 → 4, 4 → 1, 1 → 5, 5 → 9

Chris Smith, maths teacher and noted pi geek, wondered whether it was possible to animate the effect, “so people get a handle for how segments are put together and then the dynamics of it.” The (very cool) software used in the original visualisations is most-often used in biology, though it would probably have been possible to do something here… I’ve heard it remarked that computer scientists like to “make” things, as a first resort, rather than last (gross generalisation, but I include myself in it…). Since there would be work involved in automating Circos, I thought I’d have a bit of fun with version 4.5 of the Windows Presentation APIs*.

The result was Pi Wire, which has been thrown together in the last few days. The application exposes parameters that adjust what’s being visualised, and it animates the process, as well as saving final (or intermediate) images. It renders pi, e, or φ to a variable number of decimal places. Each connection, in the example above, is rendered in colour, depending on the value of the (first) digit – 3s are pink/purple, 1s are orange, etc. It doesn’t look like much when working with only five decimal places, but the example shown in the picture uses the first 10,000 digits of pi. Chris blogged a little bit about the maths and patterns here.

Critically, the animation means a picture can be built up bit-by-bit (for demonstrating to kids, for example). As well as tweaking the render settings, we can adjust colours, line properties, and so on. We can switch on or off individual segments/digit values. The golden/orange graphic (right) shows only the progressions (for the first 100 digits) which start with 1. It shows the spread of which digits usually follow a 1.Pi 1000 digits - draw 1 only

It’s a bit of a rush job, though it’s (fairly) easy to use and hopefully interesting. Chris is certainly having a lot of fun making pretty pictures!

* Which I’d been using for work anyway (an old link, but one example).