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.