How to Write a Secret Code for Your Best Friends

Learn how to create your own substitution cipher to send secret messages to your friends. HowTo: Family Edition: family how-tos that actually help.

1. Make your key. Write the letters A through Z in a straight line across the top of your paper. Directly underneath each letter, write a different letter from the alphabet in a random order. This is your 'cipher key' that tells you which letter replaces the real one.
2. Write your secret message. Think of a short sentence you want to send. Look at your key, find the letter you want to write, and look at the letter directly below it. Write that new letter down instead. For example, if A is paired with X, write X every time you want to say A.
3. Share the key. Ask a grown-up if you can copy your key onto a second piece of paper to give to your friend. Without the key, your friend won't be able to turn your secret letters back into real words!