When they ask for treats at the grocery store, ask them if they have any money.
Give them opportunities to earn money.
Let them make bad spending decisions and learn the lessons from doing that.
Teach them about and let them practice investing.
Teach them how to work hard by example and practice.
Teach them about credit scores, income statements, net worth, and other economics and basic finance concepts.
Offer to give them a certain amount of money (interest) if they save n $ and keep it for y days, possibly in a savings account.