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Secret Writing

Three short lessons on codes and how they are broken: shifting the alphabet, counting letters to crack a shift, and why a longer key is harder to break.

For grown-ups, from what CipherForge teaches children at Spark & Anvil.

  1. Lesson 1Shift the alphabet
  2. Lesson 2Count the letters
  3. Lesson 3Longer keys
At the table · a grown-up and a child, 7 or older

Make a cipher wheel

You'll need: two paper circles of different sizes, a pencil and a paper fastener (or pin).

  1. Write the alphabet round the edge of each circle and pin the small one on the large one.
  2. Turn the inner wheel three places. Write a short message in code.
  3. Swap messages and decode each other's.
  4. Try a mystery shift and crack it by counting letters.

Print the guidebook (all lessons + the table activity) →