Used to be that cash was king for teaching the kids, since gold coins are tangible, stackable, and you can certainly feel the pain when you part ways with them! Especially if you use a four-jar system - one each for spending, saving, giving and growing - kids can give each of those dollars a job all its own.
But these days so much happens behind the scenes as we swipe or tap our cards for everything. What money lessons are the kids absorbing?
Our brains work differently when we've got cash in hand than when we use a card. As my seven year old makes his way to the dairy to buy what the kids call "gay bacon", his mind balances the pain of handing over the money with the pleasure of getting that rainbow-coloured ribbon of rolled sugar.
It's a trade-off, and since he obviously feels it's worth it, he lets go of the money and brings home the bacon. The feedback is immediate.
If I take him grocery shopping and pay for the real bacon with eftpos, though, there's no trade-off for him to see - he thinks I can pick up whatever I want with the tap of a card, without letting go of anything. It's like a parcel passed into the future, to whenever I check my balance next or get my credit card bill in the mail a month later.