Book excerpt: The Secret Code Book is a short introduction to substitution ciphers. The chapters ease young readers into the concept of rotation ciphers and work their way up to the Vigenère cipher. Along the way, readers will also learn about geometric approaches to secret codes such as the Pigpen cipher. As a bonus, there is a brief description of frequency analysis and how it is used to crack secret codes. frper gpbqr obbx In addition, this book actively challenges readers with practice missions where answers are listed in the back. Also, there is a cut-out rotation template that is provided to make your very own cipher disk! After reading this book, you will have all the basic tools needed to create secret messages.