Teaching kids about the bitcoin is quiet difficult because they dont know how to behave with normal money how would they understand how to work with the bitcoin they are to young.
That is the reason we must concentrate on teaching our kids about bitcoin up to their level of using money.
Kids always love buying chocolates or games, so we could explain them for many chocolates we could buy for a given money in fiats and in bitcoin payments.
Usually you could get some discounts for bitcoin payments so you can have more chocolates for bitcoin payments, that might get your child interested to ward bitcoins. Just an rough idea.