Term 2 has finished! Peter and Leandra have arrived to spend a couple of weeks with us over the holiday period, and Sam will join us at the beginning of April.

The last week of term was unusual, since the Grade 11 and 12 students were all away on cultural field trips.

For me this meant that one of my Algebra 2 classes was not present at all, one class only had two pupils, one class was halved in number, and one class was just missing one pupil.

Since around half my students were away, I couldn’t teach anything from the curriculum, so the tradition is to do an alternative ‘enrichment’ unit. I was not inspired by what had been done in previous years. Using some GCHQ puzzle books which the children had given me as presents over the years, I decided to do a unit based on cryptography. Peter agreed to help design the activity….

At the start of the week, all the students were enlisted as British Secret Service agents:

The classroom had some suitably inspiring posters:

As they entered the classroom, they were greeted with the theme tune from James Bond. I then divided them into teams, each with a team number (001 to 009 – the two girls in my period 5 class had the honour of being 007).

They were then given a message from MI6:

============================ ============================

Agent X. Mission Objective: Investigation of a Suspicious Website Target:

https://eiskaufen.ucraft.site/

Mission Overview: Your mission is to investigate the suspicious website and gather intelligence to determine if it poses a potential threat to national security. We think the website may be purely a cover up for a code transmission to a foreign agent. You will analyze the sub page <#P!-018> to determine its message and therefore its purpose and potential affiliation with criminal or terrorist organizations. Transmission Over. ============================ ============================

Peter created the message, and the website (which only exists for two weeks, so probably the link doesn’t work any more). It was a website purporting to sell ice:

It had a shop (not yet open), and a blog with several interesting articles:

But also a rather suspicious looking page:

The students goal was to decode the above message.

To start with, they underwent training in cryptography, learning how to encode and decode messages using prime numbers. They used relatively small numbers, to keep the maths simpler, but to solve the above, they would eventually have to factor the large N above into two large prime numbers.

They had an agent toolkit, which was a password protected file containing clues on how to do the above prime factorisation. To get the password, they had to set up their on encoding/decoding algorithm, and then I sent them the password, encoding using their algorithm, which they had to decode.

Once they had done the factorisation (which was not trivial), they had to work out the decoding keys, and decode the above message. When they did so, it led to another website:

The feedback I got was that they all enjoyed the challenge of the unit; one student who had also done the previous year’s unit said this year was much better – helped no doubt by Peter’s creative input.

Over the holiday period we are going to Mombasa with Peter and Leandra, to lounge on the beach. Then we return to Nairobi, pick up Sam, and go on two days safari before they all fly back to Germany together at Easter. Lesley and I then go on a staff retreat (also down at the coast). So no more blogging until next term….