Advice from trying to get Kiddo on board with money (she still thinks that paying with a card is somehow magical):

Start with basic math, using coins as quantity symbols. Over time it gets easier to blend in fractions, decimal places, place holders and ultimately the more abstract bits of money. Kiddo in her late teens needed to review decimal places in a money context so she'd understand that 15 cents is not the same thing as 15 dollars. (Math numbers on paper were not something she could abstract into "money" on her own.)