From time to time, I like to provide you with examples on how to teach boys.
As I was walking past the office, Trajan, five years old, joined me to chatter about what five-year-olds chatter about. After a couple minutes, he suddenly stopped and asked, “Is it five minutes yet?” I laughed and said, “That depends on when the five minutes started.” Again he asked, “But is it up yet? Daddy told me to be back in five minutes. Is it up yet?”
In my great maturity and wisdom, I patiently answered, “Five minutes has to have a starting point in order to terminate at a given point. If you can’t tell me when it started, I can’t tell you when it is up.” He looked at me in exasperation and, I think, a measure of pity, and said, “Don’t you know when five minutes is up?” So having a great reservoir of answers, I stooped down in the driveway and drew a line with a rock, explaining, “Time is like a line; it is endless.” That sounded pretty wise to me. Then I drew a line intersecting the time line at a right angle and told him that this is the beginning of five minutes, and then drawing another intersecting line about two feet further down, I said, “And this is the end of five minutes.” Punctuating with the rock, pounding the line, I said, “A given period of time must have a beginning so it can have an end. If you don’t know the beginning, you can’t know the end.” There. I had explained it simply, with a visual aid. I was satisfied and was sure he was enlightened. I have an ability to get on the kids’ level. When I looked up, he was just staring in wonder, and in a tone of dismissal, he said, “Don’t you know when five minutes is up?”
“No. . . I guess I don’t. Do you have any easier questions, like, where do babies come from?”

Michael Pearl