Kids is want to play games i think children is dont want to earn money the only want of kids is to buy anything that thing is very cool for children and that he know he can play that toy or what!
We can use toy for them to know about bitcoin, i mean we can connect their toys for them to know more about bitcoin, it is always depends on the situation and on how we teach our child.
I like this idea very much! You can also show them a cartoon about Bitcoin or a small video explaining what it is. Here is the video where the lady explains what BTC is for a girl: