to teach kids, or anyone, about bitcoin, you should probably first explain them about money.
and about how the current fiat system and banking system is a giant scam.
That's not easy, child's logic is not the same as ours.. IMO, as I observe my son, I bought him a piggy bank(just the plastic one)...I told him that everytime I give him a coin, or if he found one under the sofa, he must put it there and if it is full, I will bought him a new toy car, so everytime I give him a coin, he will immediately look for his piggy bank and insert the coin.. The thing is, you should inspire a kid first, tell them that bitcoin is what you use to bought them toys..Telling kids negative things would just confuse them and might probably grow without trusting...