When my son was in the ninth grade, we reluctantly agreed to let him move into the basement. Then I realized how convenient it was to get him to the breakfast table. Before, I used to stand at the bottom of the staircase and scream his name. Now all I had to do was flick the basement light off and on, and he was here.

One morning I flicked the switch, and nothing happened. I did it several more times. "I'm on my way," my son called up. "You didn't have to yell."