Never give your kids a credit card, not even those prepaid cards.  Cash is more real to a child or teen than swiping a card--they can see and know how much they have left.  Cash teaches your kids to live within their means.  Up until your kids have a steady job, give them a cash allowance that is appropriate for their age.  Tell them no more cash until next allowance day once the cash they have runs out.  Trust me this is much better than letting a teenager run amok with plastic.  Even an atm or debit card is an excuse for a kid to overspend.