Story Problem

While I was taking Maysen to school this morning, Preston was holding three balls. He said, "Too bad we don't have one more, then there would be one for everyone." I kind of chuckled at him. Then he said, "If we had five, there would be one for you". I said, "How many do you need so we could have enough for Dad?" He answered 3. At first I figured he didn't understand, because obviously we need 6. It took me a minute to realize I was the one who didn't understand. He already had three balls, so we only needed three more. Smart little boy.