Codes & Ciphers
Ciphers a solver can crack unaided.
A cipher is only fun if the solver can get into it unaided. The moment an adult has to explain the method, the puzzle is over and what is left is copying. So the useful question about any code is not how strong it is, it is how the solver is supposed to work out the method from the page in front of them.
A few teach themselves. Mirror writing announces what it is the second a child holds it up to anything shiny. A equals 1 gives itself away if you print the alphabet with numbers under it somewhere in the room. A decoder wheel is its own instructions once the two discs are pinned together. Those work from about six upward.
Others need a way in supplied on purpose. A Caesar shift is fair only if something in the room tells you the shift, or one short word is already decoded as an example. Pigpen needs its key hidden somewhere findable. And substitution with a random alphabet, the kind with no pattern at all, is not a puzzle for children: it is a lookup task, and it takes twenty minutes of joyless work.
Guides
Codes & CiphersPrintable Decoder Wheel, With Four Secret MessagesCut out two circles, pin them together, and read secret messages. Four coded messages come with it, and each one gives the key to the next.2 min read