Encryption is good example of the use of mathematics in our lives and has been used by people for secret communication for centuries. It’s used in wide area from personal data protection to country security today. Although encryption is made with computer programs with more complex methods today, it’s based on old mathematical methods. In this project, some encryption methods used throughout history will be explored and then students will write encrypted letters to their peers with these methods or their own unique methods. Moreover, they will like math with fun project activities.