I think someone could create a game about it , a game composed of story telling which as they progress they get to know more about different angles of bitcoin world which could be useful when they grew up 
it's good for kids to get to know bitcoin but wait for a little deawa to let them understand, because we can not impose their wishes because if it's still too easy for their childhood because they still need to play and in a period of growth ..let them enjoy their childhood and wait for the right time to tell about bitcoin, and I think that is effective when they are teenagers and easy to understand for them, and over time I'm sure they will understand and understand about bitcoin.