This is for pedagogical purposes. Please do not cypher actually important messages with this.
Anyway I think it can bring with little ones, and adults alike, interesting conversations around :
- secrecy
- privacy
- cryptography as counter-power
- mathematics, starting with modulo
- the duration a message can stay undecipherable and thus the kind of message to share
- computational complexity, how many permutations are available
… and a lot more!
More specifically, the bracelets are lined up for rot13.
It might be more fun to print two randomly ordered bracelets that need to be lined up correctly to en/decipher a message.