Code Club

Friday 29th July 2016

I read about Code Club when it first started in 2012, and we've just finished our first term of teaching it at Lostwithiel School.

The idea is to encourage 9-11 year olds to start programming in after-school clubs, we had about a dozen kids coming along to our club and they all made fantastic progress!


Across the country

Code Club is entirely run by volunteers, across the UK there are almost 4,000 clubs with almost 50,000 children! That's about a fifth of the total number of primary schools on the country, which isn't bad for the first four years.

Code Club itself is run the Raspberry Pi Foundation, the same organisation that makes the tiny cheap computer which is the UK's best selling PC of all time.


CS First

We've been following Google's brilliant CS First programme, and for the first term we chose their Storytelling topic to teach the kids in our club to code using Scratch, a free visual language created by MIT that runs entirely in the browser so there's no need to install anything on the school laptops.

The Storytelling topic is great because its main focus is using the tools to tell interesting stories, rather than just teach while loops in a dry manner. It's brilliant, and I bet the kids didn't even realise they're learning anything!


Looking back

I've always had a computer, we got a Sinclair ZX80 in 1980, and my parents ran a small business hiring out ZX Spectrums and Dragon 32s in the early 1980s.

I spent a reasonable amount of my childhood typing in lines of Basic code from computer magazines.

10 DIM s(60): DIM c(60)
50 GO SUB 370
60 LET z$="00"
70 CLS 

I kind of understood it, but not enough that I could write my own games.

Later on I wrote a couple of text adventures games on my Commodore Amiga and played about with the Amiga's Shoot Em Up Construction Kit, but never really seriously. I didn't learn any real structured programming until I started building websites in 1997.


Looking forward

When we're running Code Club I always think about how my life might be different if this had existed when I was young.

Everything I've learned about programming has been self taught, trial and error, or learning by reading other people's code.

The basics of coding aren't complicated, and I think they're well within the grasp of most 9-11 year olds. If someone had taught me code when I was nine I would be a much better programmer now!

Look what we've done with the current generation of programmers, a lot of whom are self-taught like me. Imagine what the next generation of programmers are going to be capable of building!

But something's been bothering me about this ever since we started Code Club, which was very clearly articulated by a Wired article back in May.

Machine Learning like Google's Go-playing AI or their self-driving cars aren't following computer programmes in the way that we're teaching kids to code, and it's only a matter of time before even the humans that created these tools aren't capable of understanding how they behave at their core.

How useful is it to be teaching this way of coding which might be going obsolete by the time they finish school?



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Google Cardboard

Friday 4th December 2015

Virtual reality has been the next big thing since I was a kid, but I've yet to be impressed with it. What I do love is Google Cardboard, VR on a budget!

It was released last year, but I've only just got around to buying one.


Where to get it

You can buy all sorts of fancy viewers, but I bought mine for £4 from eBay (I love eBay). It comes flat-pack and takes all of two minutes to assemble.



Now just download some VR apps like the awesome-for-three-minutes RollerCoaster VR, put your smartphone into the headset and be amazed!


I know it looks terrible but it's quite a lot of fun :)



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Making halloumi

Friday 13th November 2015

Years ago I got excited by cheese-making, but it went the way of all my hobbies once I realised that I needed a way of closely monitoring the temperature and humidity.

Then last week I saw that milk was on special offer in our local supermarket and thought I'd have a go at making halloumi at home. It doesn't need any special conditions because it's kept in the fridge in brine, so it's a lot easier. 


  • 2 litres of full fat milk
  • 2 tsp rennet (I used Langdales)
  • 50g sea salt (I made my own)
  • A 30cm square of cheese cloth, or a clean tea towel


Heat the milk in a saucepan to 32°C, then add the rennet. Stir to mix it completely and then cover the pan and leave it for an hour or two.

The rennet acts on the milk proteins to turn the liquid into a strange semi-solid congealed mass - this is the curd. Cut the curd into cubes about 3cm across, and use the knife at an angle to cut across it a few times. Leave it for half an hour, after which time the whey should have started to separate out. 

Put the pan on a very gentle heat and bring it up to 38°C. All the instructions I've read say to do this over half an hour, but that's very hard. It took me about 10 minutes to get up to temperature. Stir it very gently, and you'll see that the curds break up into small lumps in the greeny-coloured whey.

Line a colander with the cheese cloth and put it over a clean saucepan. Gently pour the curds into the cloth, making sure that you're saving the whey in the pan below. Once the whey has all drained off, you need to compress the remaining curds.

You could do this by simply putting a small plate on top of the curds and then resting some heavy cook books on top, or I bought a cheap cheese mould from eBay (I love eBay) which has holes that allow the whey to drain out. Leave it to press and drain overnight. 

The next day, the curd will be a hard mass, which you need to cut into blocks about 5cm wide so the brine can cure it. 

Heat the whey in a saucepan to 85°C and put the cheese into pan. Keep a close eye on the temperature, don't let it get too hot, and wait until the cheese floats to the surface. Some instructions said this will take about half an hour, but it was more like 15 minutes for me. Take the cheese out and leave it to cool.

Finally you need to make up the brine to cure the cheese in. Add 500ml of whey to 500ml boiling water, and stir in 50g of salt. Cool the liquid to room temperature. 

Sterilise a large clean jar and place the cheese into it. Top up with the brine almost to the brim, and place a small piece of cling film on top of the surface of the liquid to stop the cheese drying out when it floats. 

Leave it for a week, and then enjoy!




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Halloween Masks

Friday 30th October 2015

A quick one this week, if you're going to a Hallowe'en party this week I'd totally recommend these awesome masks from Wintercroft, a Cornish design company. Here are some examples from their website:

They're £4.50 each and are emailed to you as a PDF. You cut them up, glue the templates onto some card and assemble them. There's a video on Youtube showing how to make one.

This one took me about two hours to make, and it's great! Okay, so mine's not as good as some of the examples above :)


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Open cola

Friday 2nd October 2015

The recipe for Open Cola, an open-source recipe for a Coke-type drink, came out in 2001. I've always wondered what was in Coke so thought I'd have a go at making some with Ash and Pete.

Here's what happened.

First of all we got all ingredients together. This was no mean feat in itself, and cost about £40 - but this is enough to make several batches. We sort of followed the recipes on Wikipedia and Cube-Cola. Most of the essential oils came from an online supplier, with everything else coming from eBay (I love eBay).

Flavouring formula

  • 3.50 mL orange oil
  • 2.75 mL lime oil
  • 1.25 mL cassia oil
  • 1.00 mL lemon oil
  • 1.00 mL nutmeg oil
  • 0.25 mL coriander oil
  • 0.25 mL neroli oil
  • 0.25 mL lavender oil
  • 10.0 g food-grade gum arabic powder
  • 40 mL water (the Wikipedia recipe says 3ml but this really didn't work for us)

Put on some gloves and goggles, the essential oils are pretty fierce. Measure out the oils and mix together, as shown below left. Mix the gum arabic powder with the water until it forms a cloudy liquid, and then add the oils.

You'll need to blend these together into an emulsion, which can take several minutes in a food processor or with a whizzy stick. Eventually it will form a cloudy emulsion as shown in the bottom right. You can tell it's an emulsion because if you put a drop into a glass of water, it won't separate into a oil layer on the top of the water. Don't leave it in the food processor too long because the oils start to attack the plastic.

We (okay, I) made a right mess of this step because we didn't dilute the gum arabic with enough water, so we wasted quite a lot of the mixture. We ended up with 30g of the emulsion when it should have been nearer 60g.

The mixture smelled absolutely incredible but it didn't taste too great - very very bitter.


The two recipes we were following deviated quite widely here, so we made a new middle path.

  • 1.5kg plain granulated white table sugar
  • 750mL water
  • 30.0 mL caramel colour
  • 17.5 mL 75% phosphoric acid (particularly nasty, watch out)
  • 30.0 mL flavouring formula
  • 1g caffeine tablets, crushed up, diluted with 10ml of water and passed through a coffee filter

Put the sugar and water in a pan and heat, making sure it doesn't boil. Add the caramel, phosphoric acid (carefully!) and caffeine solution to the flavouring formula and stir carefully.

My pH sticks said that the mixture was about pH 1, so don't drink it.

Once the sugar has all dissolved in the water, adding the flavouring and stir, then allow it to cool. We made just over two litres of the concentrate, enough to make 14 litres of cola. This is what the concentrate looked like.


We diluted the mixture 7:1 with sparkling mineral water and tried it - absolutely delicious! We had a bottle of Coke to compare it with, and to be honest after our magical open source cola, the "real thing" tasted dull and lifeless.

I've since tried it with soda water (also nice) and with straight tap water and it's still great! I've had really good feedback from everyone who's tried it, although almost nobody has guessed what flavour it's supposed to be - especially since it's not brown.

So it's a winner in terms of taste, how about cost? If we hadn't messed up the first stage we would have had more like 28 litres of cola and enough ingredients left over to make another 2-3 batches. That's about 70 litres of cola for £40, which is about half the cost of buying it.


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Making salt from seawater

Friday 4th September 2015

When I told a friend I was going to make salt, her reaction was 'why bother?'. True, it's pretty cheap but I was curious to see the point where it turns from being water to being salt. We had some friends staying and their kids were really interested to see the process, so maybe your kids would like to see it too.



I wanted to get some nice clean sea water, so we went out for a sail in St Austell Bay and collected 5 litres of water from a spot about quarter of a mile offshore.



When we got back, I left it to sit overnight so any big particles settled to the bottom, and then filtered it through a bunch of coffee filters. There were a few specks in the filters, but generally it was pretty clean.



Okay, so this isn't the most environmentally friendly way I could have done it, but waiting for it to evaporate in the UK would have taken weeks. As the water level went down it became more and more cloudy.If you're doing this at home, don't use steel pans! It went a bit rusty.

Eventually it became a white crystalline sludge, at which point we ran it through another coffee filter but this time we kept the solid material.



We spread the sludge onto a piece of baking paper and dried it in the oven at about 85°C for a couple of hours, until it was completely dry.



Once it was dry, the salt had caked into large lumps, so we pushed it through a sieve. Ta da!


In total we got 134g of salt from 5 litres of water. Average sea salinity is 3.5% so the maximum yield was 175g. There was a lot crusted onto the pan, and some of the salt will have evaporated with the water, so this is about right.


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Friday 14th August 2015

I'm a massive Nutella fan, so when a friend posted a link explaining how to make it, I ran right out to buy some hazelnuts. I wanted to avoid using palm oil, and thought it would be extra awesome with coconut oil instead. I made a batch with normal oil, a batch with coconut oil and a batch with dark chocolate just to see what would happen.

Here's a quick video showing what I did:


Update: I've since discovered a much simpler version if you're in a hurry - see the end of the post for details.

  • 170g hazelnuts
  • 340g chocolate - milk or plain depending on what you like
  • 45ml coconut oil (or vegetable oil if you prefer)
  • 3 tbsp icing sugar
  • 1 tbsp cocoa powder
  • ½ tsp vanilla essence
  • ½ tsp salt


Heat your oven to 160°C (non-fan oven 180°C) and bake the hazelnuts for 10-12 minutes until they brown slightly.

Microwave the chocolate until it's just liquid and then stir to make it smooth.

When the hazelnuts are done, rub the skins off with a tea towel, leave them to cool down and then puree in a blender for about 5-10 minutes until they become smooth and buttery. If they're very fresh nuts, you may want to roast them for a bit longer, otherwise the water in them is going to react with the chocolate to form a solid mess.

Add all the remaining ingredients and continue to blend for another few minutes, until the mixture is smooth.

Strain through a sieve to remove the larger chunks (there will be some small pieces left in the mixture) and then scoff it all straight out of the bowl immediately.



Since I wrote this post I've refined the ingredient and made it much simpler, here's an updated recipe:

  • 170g smooth hazel butter (like Biona)
  • 340g chocolate - milk or plain depending on what you like
  • 3tbsp coconut oil

Melt the chocolate in a microwave and then mix all the ingredients together. Done!

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Making soap

Friday 5th June 2015

I've wanted to try this ever since I saw Fight Club! I've seen several methods for making soap, but I'm always attracted to using dangerous chemicals, so lye seemed the obvious way to go.

Lye, sodium hydroxide, is an incredibly caustic chemical with a bad boy reputation for removing fingerprints and dissolving corpses. During the second world war, Leonarda Cianciulli liquidised three victims in Italy using the stuff, and Santiago Meza López, "The Stewmaker", claims to have disposed of 300 bodies with it. 

I decided to make a floral lavender soap and a macho coffee soap inspired by The Art of Manliness. They say that coffee soap is very good for cleaning harsh smells from your hands.

I used The Sage to get the right quantities of oil, water and lye, and off I went!


Lavender soap

  • 1 litre (916g) of olive oil
  • 286ml cold water
  • 115g lye crystals
  • 20g ground lavender
  • 20g lavender flowers
  • 10ml lavender essential oil
  • Food colouring (optional)

Coffee soap

  • 1 litre (916g) of olive oil
  • 136ml cold water
  • 115g lye crystals
  • 3 double espressos (totalling 150ml)
  • 1/2 cup of coffee grounds


You'll also need:

  • Eye protection, a face mask and gloves - I can't overstate how dangerous lye is
  • 1 litre of vinegar - in case you spill lye on yourself you'll need to neutralise it really quickly
  • Thermometer
  • Bowls and stirring tools that aren't aluminium or wood - lye will eat through these
  • A stick blender - it reduces the stirring time from an hour to 5-10 minutes
  • Moulds to pour the soap into - I used four old takeaway containers with lids
  • Towels to wrap the moulds

The pictures are all from the lavender soap, but it's the same process for making the coffee version. 


First you'll need to make the lye solution. Put on all your protective gear. Mixing lye with water is extremely exothermic, and so it's really important to add the lye crystals to the water and not the other way around! If you're making the coffee version, wait for the espressos too cool, then mix with the water. Make sure you've got 286ml of liquid in total.

Do this outside as the fumes are really nasty, and add the crystals bit by bit, stirring continually. By the time I'd added all the lye, the water had jumped from 10°C to 95°C. You really don't want it to boil.

Now you need that to cool down to 50°C maximum, so leave it outside and heat the oil to about 50°C as well. Once the lye has cooled, pour it gently into the oil and gently mix together. Add the ground lavender and the lavender oil, plus the colour if you're using it, then blend with the stick blender for 5-10 minutes until it's the consistency of thick custard.

Pour some of the lavender flowers into the bottom of the moulds, then add the gloopy soap, seal the moulds and wrap in towels to keep the heat in. Leave for 24 hours for the soap to set.

The next day, pop the soap out of the moulds, cut them up and leave to cure for 6-8 weeks. This allows all the lye to react with all the oil to make soap, called saponification.

Here's a short video I made of the process:

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Making butter

Friday 24th April 2015

If you've never made butter at home, I'd really recommend it. The whole process takes ten minutes, and it's magical when the cream suddenly becomes butter. You can make it by hand if you like, but it's a lot quicker with a blender.

I made a short video of it, sorry about the dodgy camera work:

Here's what you'll need to make 275g butter:

  • A blender with a whisk attachment
  • 600ml double cream
  • 1 tsp salt
  • 1 litre ice-cold water

Put the cream into the blender and turn it on. After 3-4 minutes it will become whipped cream, and you might need to scrape it back into the bowl. A couple of minutes more blending and it suddenly changes texture into yellow butter with a watery buttermilk. Pour out the buttermilk into a container, it's great for making cornbread and pancakes, or you can just drink it.

Now you need to wash the rest of the buttermilk out of the butter to increase its life span. Add a cup of ice cold water and knead the butter with a spatula. The water will quickly go cloudy. Pour the water out and repeat twice or thrice until the water remains clear.

Add 1 tsp of salt and mix well into the butter. The less you handle the butter the better as it will melt, so I found a pair of butter pats in an antique shop which allow you to work it without warming it up.

You could also mix in some herbs, I used thyme and garlic which is perfect for spreading on toast for a snack.

Once you've got it into the right shape, refrigerate and enjoy!


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What's this about?

Hi I'm Mat and I'm addicted to new hobbies. I used to think this was a bad thing but now I'm embracing it.

Writing them all up in this blog encourages me to finish projects, and helps me keep track of which ones I've tried.

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