One of the things that drives My Beloved Wife crazy is lights being left on.
For a very long time, Middle Son wanted all lights on all the time. I can remember when we would go over to his grandparent's house (my ex's parents). Middle would immediately walk through the house and flip on every light switch. Grandpa would follow around behind him turning lights back off. Sometimes they would do several laps around the house.
MBW has been working with Middle on the concept of turning lights off. A couple of nights ago Middle was getting a snack after dinner. We had left some of his dinner on the table as we often do. The lights were off. Middle walked into the dining room and turned on the lights. He sat down and ate. Then he got up, turned the lights back off, and went back upstairs.
MBW was very excited. It is nice to see it when Middle makes progress.