Introducing Caeser Ciphers to children in the range of 4th-6th grade comes with a challenge - mostly, attention span. While translating with a given cipher is quick and easy, how could you introduce the concept, through the form of a paper/asynchronous medium, of cracking codes, in a fun, non-tedious, engaging manner?

Also, any general ideas on cool things to include related to Caeser Ciphers in general?