At Bletchley Juniors Codebreaking Club this week we used a spiral code. The activity was the food chain. I encoded a chain of either three, four or five plants/animals/birds in the wrong order. After they had decoded the creatures, I gave the children pictures which they had to match to the creature, then put in the correct order. As the children became more confident I gave them spirals which went in a different direction. I even sneaked in a bit of Ancient Greek, explaining the meaning of phytoplankton and zooplankton.