5 Secret Code Ideas for Kids to write a Coded Letter

Oh how I loved secret codes when I was a kid.  The ability to write a coded letter without anyone but the recipient was just plain fun. Today on Kids Activities Blog we have 5 secret codes for kids to write their own coded letter.

secret codes for kids to write a coded letter - envelope with the word confidential written stamped on the outside - Kids activities blog
Let’s write a secret code!

5 Secret Codes for Kids to write a Secret Words Letter

Shhhh…don’t say it out loud! Write a secret coded letter for someone to decode (or try to decode). Use these 5 secret code examples as inspiration for your next secretive adventure.

1.  Reversed Words Letter Code

types of code backwards - reverse the words
Read this secret code backwards

This is a simple code to solve – just read the words backwards!  Even though it seems simple once you know the secret, it can be a hard one to figure out when you don’t.


Answer: Have a fun summer

Half reversed alphabet ciper written out on notebook paper - Kids Activities Blog - ABCDEFGHILJLM on top line with NOPQRSTUVWXYZ on bottom line
Top line is first half of alphabet and second line is the second half for this cipher.

2.  Half-Reversed Alphabet Letter Codes

Write out the alphabet letters from A to M then write the letters from N to Z directly below them. Simply exchange the top letters for the bottom letters and vice versa.

Decode: QBT

Answer: DOG

Block cipher letters a-e - Kids Activities Blog - secret code to write
A block cipher always has a key.

Number Lettering Code Variation

Just like seen above in the half-reversed alphabet, you can assign numbers to letters in a tricky way and then substitute those numbers for the letters in the words and sentences. The most common numbers the alphabet 1-26, but that is easy to decode.

Can you come up with a better number lettering code?

3.  Block Cipher Secret Codes

Write the message in a rectangular block, one row at a time – we used 5 letters in each row (alphabet letters in order A-E).

Can you figure out what the KEY is to the block cipher pictured above? Each letter is shifted one place in the second row. You can make any key correspond to the rows making it as simple or complex to figure out. Then write down the letters as they appear in the columns.

Decode: AEC

Answer: BAD

4.  Every Second Number Letter Code

code 2 - read every second letter in the message
Rotate through this code until all the letters are used.

Read every second letter starting at the first letter, and when you finish, start again on the letters you missed.

Decode: WEEVLEIRKYE – STUOMCMAEMRP (mistake made on lower line)

Answer: We Like to camp every summer

5.  PigPen Secret Code

The PigPen code is easier than it looks and is my children’s favorite.  First, draw out the two grids below and fill in the letters:

pigpen code key - coded letter alphabet
Here is your code key for pigpen.

Each letter is represented by the lines around it (or pigpen).


Decode: image above


6. Simple Number to Letter Code

simple letter to number code with three lines written on white paper - Kids Activities Blog

A simple number-to-letter code for kids is the A1Z26 cipher, also known as the alphabetic code. In a number to letter code, each letter of the alphabet letters is replaced with its corresponding position in the alphabet, so that A=1, B=2, C=3, and so on…

Decode: 13-1-11-5—1—3-15-4-5

Answer: Make a code

Write a Coded Letter

We practiced writing our names and silly words before moving to coding whole sentences.

Related: Write a Valentine code

The letters and messages you can write can be fun, but make sure you send along a key so the recipient can figure it all out!

This article contains affiliate links.

Secret Code Toys for Kids We Love

If your child loved these secret code activities, then you might consider some of these fun and mind-stretching toys:

  • Melissa & Doug On the Go Secret Decoder Deluxe Activity Set and Super Sleuth Toy – gives kids a chance to crack codes, uncover hidden clues, reveal secret messages and be super sleuths.
  • Secret Codes for Kids: Cryptograms and Secret Words for Children – this book includes 50 cryptograms for children to solve including secret and hidden words written as number codes from super easy to super difficult.
  • Secret Code Breaking Puzzles for Kids: Create and Crack 25 Codes and Cryptograms for Children – this book is good for kids 6-10 years old and contains clues and answers for kids to make and break their own codes.
  • Over 50 Secret Codes – this entertaining book will put kids code-cracking skills to the test while learning how to disguise their own secret language.

More Writing Fun from Kids Activities Blog

How did your coded letter turn out? Did you keep your message a secret?


  1. Great ideas! I’ve never seen Pig Pen cypher before. I am pinning this post!

  2. oh, how much fun my secret spies will have with this this afternoon. knaht uoy! Lol.

  3. I loved secret codes when I was a kid! And then there are the “secret” languages such as Pig Latin and Ubbi-Dubbi! My own mother was an expert at speaking Pig Latin to Dad when my siblings and I were too young to understand it and she didn’t want us to know what she was saying!

  4. i made up my own secret code when I was little but these are some great suggestions to get kids interested.

  5. My son LOVES secret codes and I’ve found them to be a GREAT way to sneak in some word work. Thanks for sharing at the After School Linky Party. I’ll be featuring this post tomorrow. Stop by to check it out and share more great ideas from the quirky mommas!

  6. Oh, so many good memories from this!! PigPen was my favorite and number 4 is great too. Thanks so much for sharing it at the Less laundry, More Linking party.

  7. This is SOOO much fun, my boys will LOVE this!!
    On behalf of Lisa, Cindy & myself, thanks so much for sharing your links at our “Best Of The Weekend party”! I am pinning all to our party board and pinning this to another big board too.
    We hope to see you again when the party kicks off again Friday eve at 8PM EST.
    Have a great week!

  8. aha! i can imagine DD’s reaction to this.. a fun game for a long drive. thanks for sharing!
    -Reshama @ StackingBooks.com

  9. in number 4 there should be an s before the t on the bottom line

  10. Thank you for step by step tips very helpful. I love your blog.

  11. Jonathan Vander Woude says:

    AWSOME!!!!!!!!!!!!!!!!!!!!!!!! So great!!??

  12. Eliana Marcela Sanchez says:

    I absolutely love this advise for the month of fun activities. Too bad my son is all grown up and won’t enjoy any of these activities?. However he had a great childhood. ???

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