Secret Agent Friends

Sharing secret messages with friends and family can be fun. With our fun decoder activity, you can now create secreted coded messages that only someone with the decoder can decipher. Make two matching decoders so you and a friend can swap messages and quickly decode them.

DIY Decoder Activity

What you’ll need:

  • Colored pencils/crayons
  • Pen or fine-tip marker
  • Card stock/poster board/paper plates
  • Scissors
  • Glue stick
  • Paper fastener


  • Print out our printable decoder template onto card stock, or print on regular paper and then glue onto the flat part of paper plates. 
  • Carefully cut out the two circles.
  • Use a pen or fine-tip marker to write one letter in each space on the large circle, until you have the complete alphabet written out.  You can go out of order to make your decoder extra secret!  If you’re making a decoder for you and a friend to decode each other’s messages, be sure to use the letters in the same sequence for each wheel.
  • Write one number in each space of the small circle. 
  • Use colored pencils or crayons to decorate your decoder wheels.
  • Stack the two circles on top of each other, making sure that the center on the big circle lines up with the center on the small circle. Carefully poke a hole in the middle of all the wheels and push a paper fastener through the hole.

Your decoder is now ready to use!

Set the Code

Before you can use your decoder, you need to set the code. This is the fun part because you can change how it’s set every day to keep your code secret. It’s easiest if you decide each time you set the code what 1 is equal to. One easy way to remember your code is to have 1 equal the first letter of the day of the week. So on Monday, 1 equals M. That means that when you spin the wheels, you line up the 1 on the little wheel with the M on the big wheel.

Secret Messages

Once you’ve built your decoder and set your code, it’s time to write your coded message. Keep it short and simple to start. For the first few messages, it may be easiest to write out your message first, leaving space underneath each letter to write the coded letter.

Using your decoder, write the corresponding coded letter under each real letter. For example, if you write a 3, find the 3 on your decoder wheel on the small circle and then note the corresponding letter on the inside wheel. Write that letter down. Do the same for all the letters in your message. Be sure to keep your decoder wheel set the same for the entire message (so in our example above, the 1 on the outside wheel would match the M on the inside wheel the whole time).

Transfer just your coded letters to a piece of paper you can give to your secret agent friend!

Decoding the Message

When you get a coded message, start by setting your wheel to the agreed upon code (again, in our example that means the outside 1 matches the inside M). Letter by letter, write down the correct letter from your decoder wheel until you’ve deciphered the entire message.

If your child is enjoys this activity, he or she may also be interested in learning more about how video games are created through special code.  GameStart is a local non-profit that helps kids learn about science and technology through video games.  The GameStart team visits Mott each week to teach Mott patients how they can create and experiment with video games.  Check out this Minecraft block building project the GameStart team provided for our Campers.

Other science and math projects from Camp Little Victors: