As part of teaching our kids about money, I insisted on not only using physical currency for items the kids decided to purchase with "their own money", but on r

As part of teaching our kids about money, I insisted on not only using physical currency for items the kids decided to purchase with "their own money", but on ringing them up in a separate transaction and having my kid actually hand over the currency and receive the change and the item. (This doesn't work for online purchasing, of course, but anything in store, we'd do this way.)