Many years ago, when United first started using Airbus 320s, a 7 or 8 year old girl and her aunt or grandmother were sitting across from me. The airbuses have LCD screens that descend from the ceiling, something I'd seen only a few times before -- and this pair had probably never seen them. When all the screens came down at once just after we started taxiing (so that they could play the safety video), the girl and her companion looked at each other and just burst out laughing. I couldn't help but laugh with them: the lesson I learned, long before having a kid of my own, is that kids know where the joy is hidden in little things.