Code wheels for Super Spies

What: Code wheels made as part of the Secret Agent mission for Kid 7’s birthday.

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Codebreakers at work making their equipment. One day I’ll tell them about Bletchley Park.

How: The kids found a briefcase that contained code wheel sheets, split pins, scissors (they got to keep a pair each, I’d ordered a bulk pack from an education supplies online store), and a new code message written in rotary cipher (moved on 7 places for a 7th birthday). I got the code wheel sheets as a download from The Science Museum in the UK and printed them myself. They’re the kind that have two wheels that you have to cut out and attach together, so I needed to print them on something sturdier than normal printer paper but that would still go through our printer. That was tricker than I expected – I used to use 110gsm paper for that sort of thing but the local office supplies store only had 80gsm or 210gsm (which won’t feed through a printer). Eventually I found some fancy stuff used for printing wedding invites etc, and that mostly worked OK but was not as cheap as I’d thought it would be.

So then the kids happily went and sat in the loungeroom and cut out and assembled the code wheels. I thought that might be slower and more confusing, but they all did it quite easily. Kid 5’s age group might have been more erratic with the scissor precision, but the 6-7 year olds were perfectly fine and didn’t need explanation on how to make the wheels at all, just intuited it.

We ran into a problem though using the code wheels to translate the message. Remembering which wheel was code and which was decode was very tricky for the kids (though pretty straightforward for kid 9 and kid 11). I’d also gone seven places back instead of forwards. And the code wheel itself had lots of extra characters so wasn’t just a straight alphabetic rotation. Which would have been fine if I’d used the same code wheel to make the message. But I hadn’t – there are lots of online scripts to encode messages and I’d used one to write my rot-7 message so that I wouldn’t make any mistakes. The result was that the message didn’t actually translate. I had to redo it on the fly using a spare code wheel, and I did make at least one mistake. But eventually the group of us all worked out that the message said “Towel Up!”, and ran for the bathroom.

Spy gear gained and used in this exercise: scissors and codewheel.

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