I think hands on learning is the best form of learning. I got 3 kids, 12, 11, and 5. The older 2 have their own on-chain wallet (Nunchuk) and lightning wallet (Breez) that they manage themselves. When I went through the setup with them on their phones, I got them to setup the wallets, send a small amount into the wallets, delete the wallets, and recover them. They understand that the on chain wallet is for savings and the lightning wallet is for spending. They get income from handouts by elders during Chinese New Year (it's a cultural tradition) and also when we take cans and bottles back to the recycling center (we split the money equally between myself and the two older kids). Then they decide how much money they want to save up whenever there is income, and convert the amount to bitcoin. We still live in a fiat world, so they keep a small amount of fiat as spending money.

I'm still custodying the 5-yr-old's coins, but will setup his wallets with him when he turns 8 or 9, depending how technically competent he will be at the time.

Besides getting them hands on with bitcoin, I buy books and toys related to bitcoin. I also talk to them about value, money, and bitcoin whenever they are willing to listen. I try not to make the bitcoin talks sound like a lecture, but just casual talks, and would stop whenever I feel they start to lose interest. I try to answer any questions they have to the best of my abilities and would look it up online together with them if I can't answer their questions.

I find it much easier to start young, because the younger kids are, the more important you are to them, and the more they will actually listen to what you have to say. It doesn't mean I want them to do what I say, but at least they will listen to my words and not automatically tune out once I open my mouth.