Well I think Bitcoin won't be a big help for a kid to learn to save money. Bitcoin is not a factor. A factor to kid's saving money is his control to the money. He should be wise enough on how to use the money properly. Use it for good purposes not on luxuries or desires.
I think so, we should teach kids using fiat on how they can manage the allowance given to them. It is more accurate if we teach them first with money on their hand not digital currency. On how they should used it wisely and also by teaching them the importance of saving it. By teaching them that money is hard to find and also by telling them that we should work for us to have money. And if kids know it, i know they would give importance in saving it.