Print out the decoder and cut out the circles.
Place the circles so that the smaller circle with letters is on top of the bigger circle with pictures.
Make a hole in the middle of both circles and use a paper fastener to attach the circles.
Make your code key by selecting a letter on the top circle and a picture on the bottom circle, for example letter ”R” and Ruby’s picture.
Once you have your code key in place, see which which picture represents each letter and draw your message. Let your friend decode the message by using the code key.
With the help of decoder you can make your own code key and write secret messages!