At Bletchley Juniors Codebreaking Club this week we covered naval flag codes. The first activity I gave the children was to make a set of flags for the digits 0-9. I had printed sets of coloured flags which I then cut up so that the children were left with lots of red, blue, yellow, white and black pieces which they had to fit together and then glue on to backing card. The next activity was to decode a printed message: I had swapped some of the letters for the appropriate naval flag. Each message contained a problem e.g. hungry rats have eaten the mainsail! The children then had to find the problem in a codebook I had made and find the solution, then match these to code-numbers. The final activity was to set their flags to match the code-numbers, and send a message across the hall to another ship: the children on this ship looked up the code-numbers in their codebook to find the solution and send the item (in this case a new mainsail) across the room.

The children really enjoyed these activities. They liked the hands-on, problem solving element of making their flags, and it was the first time they had used a codebook. One parent was particularly thrilled as their father was in the navy as a signaller so it provided a nice link to their past.

This week at our Adults Board Games Club we played a new game for us, Abalone. We think the game has promise, but were hampered by Anna’s post-flu fuzzy brain, and some very badly translated instructions. We had a couple of games of Mancala to make up for it.

This week at Bletchley Juniors Codebreaking Club I arranged a codebreaking challenge. This was a recap of some of the codes we have explored to date (Pigpen, Caesar Shift, Polybius Square) for the children who have attended since the first week, and new material for the children who have only recently joined us. I split the children into four teams, which I named after Greek gods and goddesses (Zeus, Hera, Athena and Hermes). (This club is rapidly turning into a crash course in Greek mythology!).

The first challenge was to decode sentences describing an animal, then draw the answer. The second challenge was a treasure hunt: I had hidden envelopes around the hall and the decoded message told the children where to look. The third challenge involved deciding which of a set of Medieval objects was the oldest (sets included crowns, swords, arrows and shields).

Further challenges included: addition and subtraction questions; sentences describing Luke Skywalker (e.g. I have a twin sister); deciding which shape is not symmetrical; deciding which number comes next in a sequence; and adding a nought and a cross to make a pattern symmetrical. One team even got as far as decoding the Riddle of the Sphinx, and having a go at figuring it out.

Overall this was another very enjoyable week, with a real buzz in the room when the children brought me their answers to check and collect their next challenge.