Turn your class into code-breakers! This free 8-page printable pack teaches children aged 7–10 how a shift code (Caesar cipher) works. Children make their own code wheel, crack four coded messages, then write secret messages of their own. What’s included: A cut-out code wheel to make with a split pin A clear explanation of the shift code, with a ready-made code strip and blank strips for any key Four coded messages that get harder, ending with a “mystery key” challenge where children work out the key from a clue A “write your own secret message” sheet A detective case file template for planning and solving a mystery A Junior Code-Breaker certificate Full answers and notes for teachers Curriculum links: Maths: counting on and back, patterns and reasoning, and working out an unknown Computing: following and reversing an algorithm, and an introduction to encryption English: careful reading, spelling and writing; the case file supports planning a mystery story You will need: scissors, pencils and split pins (paper fasteners). Printing the wheels on card is optional but works best. The pack takes 45–60 minutes and can be split across sessions. It works well for whole-class lessons, small groups, enrichment, puzzle clubs or end-of-term activities. It features Izzy Bell, the young detective from the Izzy Investigates stories. Suggested tags: code breaking, Caesar cipher, shift code, KS2, puzzles, problem solving, mystery, detective, computing, encryption, reasoning Age range: 7–11