This is absolutely coming from my own experience with my son, but I though it was worth sharing.
Greenlight is a website/app that allows parents (and selected others) to add money to a child's "bank account" for them to use via debit card - which can be personalized!!
You may attach an allowance and tie that money to chores they do around the house. (The first time my son "forgot" to take out the trash and only got a portion of his allowance that week, it made quite an impact!) This app also allows your child to save money and earn interest, plus make guided investments! All of this, including where your child can make purchases, is controlled and monitored by YOU!
My family has been extremely pleased with Greenlight. Click below to find out more about it.