Make a Decoder

“I taught myself how to program computers when I was a kid, bought my first computer when I was 10, and sold my first commercial program when I was 12.” - Elon Musk


Reading code is sometimes described as learning a new language. Coding often uses weird symbols and letter combinations. Learning how to read this strange vocabulary can be tricky, but it can be fun as well.


Learn how to code and decode words and sentences using a special device called a decoder. You can make a simple decoder with paper, scissors, a paper fastener and something to write with. First, cut two circles, one smaller than the other. Around the outside edge of both circles write the alphabet, from A-Z. Make sure the letters are the same size and spacing so they can match up with each other easily. Make a hole in the circles and then use the paper fastener to put them together. You can also use a pencil or pen through the middle to hold the circles in place. They should be able to turn easily.

Write some words or simple sentences for a friend or family member. Using the decoder, line up the letter A on the larger circle with a different random letter, like the letter O, on the smaller circle. Keeping the decoder lined up the same way, translate your sentence into a code. For example: A sentence like “THIS IS FUN” would translate to “GVWF WS THA.” Now you can give that sentence to someone along with the Key A=O and see if they can decode it. Try longer sentences or have a race to see who can decode the fastest.


This program has been designed for you to share with your child. Read the material together, ask questions and encourage your child to ask questions. Then nurture their curious mind by doing the activities with them. Books included are available via CPL’s digital library (with a library card).