Is it too early?

At what age are children able to understand basic economic ideas? Since economics is loved in our household, the gardener and I tried an experiment with B to see if he was "rational" enough to respond to incentives. He has wanted the featured garbage truck in the worst way for months now. Every time we went to Target, we had to stop by the toy aisle and look at the garbage truck. We explained that we can't just buy a toy whenever the mood struck, but that some things needed to be earned. So we would find ways to give him some loose change every now and then, but it wasn't becoming an effective teaching method.

We started a payment method for doing one chore everyday for 25 cents each day, however, that fee was subject to a bad behavior tax. Whining, fighting, arguing and so forth resulted in a deduction of the weeks total. Well, after a few hard fought weeks, a parental contribution plan and collecting recyclables, B earned enough money to purchase the garbage truck. Interestingly enough, after the payment plan has ended, behavior on his part has improved. Way to go Buddy!!