## A “knowledge puzzle” in Harry Potter

In the first Harry Potter book, our heroes have to find two useful potions hidden in a collection of seven bottles. The clues are given in the book, but one of the clues refers to the biggest and smallest bottles, and the reader doesn’t know which those are. Can we solve the puzzle anyway? (Photo by Chris Liverani on Unsplash)

## Searching for the magic hexagon

In the same way that there are magic squares, where every row and column add up to the same sum, it turns out there is also exactly one (non-trivial) magic hexagon. Although this solution can be worked out mostly by hand, it was interesting to explore the different approaches to writing code to search for it.

## (Yet another) solver for the Countdown numbers round

There are many, many Countdown solvers on the internet, but I think there is something new about my approach.

## Two pictures in a grid of flashing lights

By carefully choosing their frequencies, you can make a grid of flashing lights show two different pictures every now and then.

## Decoding a Morse code Easter Egg

One of the sports in the Wii Sports Resort game is Island Flyover, where you get to pilot an aeroplane round the island and its surrounding waters. There is a lighthouse, and when you fly near it, you hear a sound very like Morse code. My younger two children and I decided to see if this really was Morse code, or just something made to sound a bit like it. Our first job was to capture the audio while a player flew the plane near the lighthouse. This is what we got: This was going to be tricky for us to analyse, so, in Audacity, we applied a high-pass filter to try to cut out some of the engine noise,

## A modified escapement design

A previous post described a Lego implementation of an escapement mechanism similar to one I’d seen in the British Museum. Recently, Zach and I built something a bit closer to the actual Tompion escapement. The pins are all in a line round the wheel, and the pallets are also in a line, offset around the circumference. It still has the difference that the interaction between the pins and the pallets takes place on the side of the wheel, rather than the top. Pleasing that this one worked too!

## Binary Email Lights

[This is a guest post written by Zach.] I’ve been using a Raspberry Pi as a desktop for a while now and it has been working great, but one annoying thing was that I had to turn on both my monitors (in case the mouse is in the wrong one) when I wanted to check my email, so I thought to make a light box to tell me if I had an email. Also, flashing lights are always cool. I, with my dad, built a display box with three LEDs so it can show up to seven emails in binary. Hardware The hardware side of this project was pleasingly simple because the Raspberry Pi has built in GPIO pins. What

## Pytch: ‘Scratch-oriented programming’ in Python

An idea I first started thinking about and working on over four years ago — a stepping stone in the journey from Scratch to Python — finally has a public prototype. https://www.pytch.org/ Scratch is a wonderful system for beginning programmers. It has a visually attractive environment, a way of creating code with a drag and drop system which avoids the possibility of syntax errors, and a natural concurrency model, where multiple ‘sprites’ all obey their own ‘scripts’ at the same time. At some point, learners want to explore text-based languages. Python is very popular in schools, and of course it is heavily used in the real world too. When trying to learn Python, a learner coming from a Scratch background