# Author: Ben North

## A set of Scratch worksheets

The school my three youngest children go to runs after-school activities, and I was part of a group of volunteers who ran an ‘Advanced Scratch‘ course. This was aimed at 10–12-year-olds who had done a reasonable amount of Scratch already, and wanted to explore more. We spent several sessions developing a much-simplified version of the great puzzle game SpaceChem, and then a few standalone projects. It went pretty well, with most of the students getting a lot done. As part of this, I wrote a set of worksheets, which I’ve now tidied up and made available under CC-BY-SA in case they’re of interest to anyone else: Scratch worksheets 2017/18 (Image above contains content copyright The Scratch Team, used under CC-BY-SA-2.0.

## An interesting piece-fitting puzzle

Via mathblogging.org, I came across Math=Love’s blog entry describing a piece-fitting puzzle, and thought it would be interesting to solve it exhaustively and answer the question in the blog entry: So far, we have found two different possible solutions. I’m looking forward to collecting data to help determine if there are more! I did this via a Jupyter notebook, and the results are here. I confirmed that the two known solutions are the only ones, up to symmetries.

## Remote display for pinball machine

To be able to watch our pinball machine’s display from anywhere in the house, my son and I put together a system using a logic analyzer and a Raspberry Pi to broadcast it as streaming video.

## Simpler exponential MazezaM level family

Following on from the previous MazezaM-related post, Aaron Williams and I swapped a few emails about my family of MazezaM levels whose solution lengths are exponential in their sizes. Aaron put forward a simplified family of such levels, and I have now produced an animated demo: Full write-up and demo on GitHub.

## ‘Splat the zombies’ 3D game

I recently got another long-running collaboration to the point of having something to show — a first-person shooter in the browser. This was an idea which Sally, my youngest, had. She drew a bunch of house fronts, and also some ‘zombies’, and then a map of the world where the action takes place. The result is hosted on GitHub pages: It requires a WebGL-capable browser, and I have not put effort into graceful behaviour if this requirement isn’t met. There are some more details, and also the repo itself, on GitHub, although it’s just a dump of the final state of the work rather than a useful history. It was good to experiment with Blender and BabylonJS in the implementation

## Exponential Mazezam level family

As a correction and follow-up to a previous post, I constructed a family of Mazezam levels whose solutions are exponential in the size of the level. Many thanks to Aaron Williams for pointing out my error to me. Full write-up and demo on GitHub.

## Joining and mapping government data sets

A while ago, the principal at the primary school my children attend remarked at how time-consuming it was for her to manually collate two different sources of information on schools, and cross-reference against a map of schools’ locations. Her task, as I understand it, was to find nearby schools who might want to pool their ‘resource hours’ with our school and thereby share a resource teacher. To allow schools to do this, the relevant state bodies publish PDFs listing the resource hours allocated to each school, as well as the number of ‘permanent resource posts’, which is also relevant to the pooling discussions. The department also have on their website a mechanism for finding a school by map. Separately, I’d

## Bletchley Park ‘Rectangling’ and LDPC codes

For now, this is my final post arising from the General Report on Tunny. I looked at the connection between: ‘Rectangling’, part of the cryptanalysis performed by the Bletchley Park codebreakers on the Lorenz cipher, and Belief Propagation decoding of LDPC error-correcting codes. See the write-up and code repo for details.