I helped my boys buy stocks / DRIPs when they were about 8 or 9. We started w/Wrigley's and then moved on to McDonald's and then our local power company. They enjoyed going to eat at their restaraunt and seeing their power trucks out and about. We used their birthday money...tracked the stocks in our homeschool classes, etc. Their investments are doing quite nicely.
As they aged we did the multiple piggy banks for tithing, saving, spending.
Then we opened accounts at the Credit Union.
Then we opened each joint checking accounts w/Mom as joint owner.
Then we learned about balancing check books.
Then we got them debit cards when it was time and they are both
just now getting ready to get their first credit cards to be used in a hopefully carefully controlled environment.
They also each now have Roth IRAs and one has a 403b. Each have multiple CDs and savings bonds as well and operate on a budget/spending plan. Paid cash for vehicles. Both at home still have nice emergency funds and other savings/escrows set up and have quite nice net worths for their ages.
So far - so good!