Substitution is a new concept for kids. Not something they can readily understand. So you need to explain that in terms of a game. Kids know what secrets are. But from their point of view, why even talk about it if it is secret? Why can't we go to another place and talk secretly? Why do we need to talk secrets in public using substitution? Since they do not see obvious need for it in their daily life and there are workarounds for it, they do not get why there is a need for substitution.
By the time we explain all these to them, they would have already lost interest, or context and would easily forget the whole thing.
Children learn substitution with language. Hand signs and words are substituted for the objects, feelings and actions they know inherently. It’s tempting to apply adult context on children but it’s a mistake.
Encryption might not even need much any explanation, just using familiar terms: kids come up with "secret languages" all the time between friends and siblings.
> Kids know what secrets are. But from their point of view, why even talk about it if it is secret? Why can't we go to another place and talk secretly? Why do we need to talk secrets in public using substitution?
Connect this to surprise gifts and birthday invites. Or another thing that resonates with them.
Explaining locks and their purpose ain't any easier. Just yesterday, my daughter asked me why I'm locking the extra set of doors we're normally keeping open, and when I told her about the just-issued warning about burglaries in our area, well, there's a lot of context to explain before a 5yo gets why locking the doors is the right thing to do in this scenario.
I mean, there's always a lot of explaining to do with kids anyway. So far, I've never had trouble giving them real explanations and letting them know when they're simplified.
By the time we explain all these to them, they would have already lost interest, or context and would easily forget the whole thing.