While playing Monopoly with my 5-year-old, I gave him a $100 bill to pay $12 in rent. He wasn’t exactly happy, but he figured out that he owed me $88 and then figured out how to make that amount with the available bills. Several years later, while walking through the forest, my 7-year-old daughter looked down at her feet and said, “I wonder how many steps I’ve taken in my life.” After a few silent shouts of joy upon hearing her curiosity, I replied, “What a great question. How would you figure that out?” Fast forward to a few days ago, my 10-year-old son was grocery shopping with me. “Can we buy this bag of pistachios?” “We don’t need pistachios,” was my reply. “Ple-e-e-ease?” accompanied by puppy dog eyes. “Okay, but get the small bag.” “The big bag is a better buy,” he replied, “because, look, this one is 8 ounces for $6, but the bigger one is twice as big for only $9, which is less than twice the price.” We went home with a big bag of pistachios.