Someone mentioned the 1/2 tip for children. This is FACT per 1990's. If children are in the same room as parents and are causing LESS stress and work for a steward than an extra half cabin, 1/2 tip is proper. I know this is picky, but some parents these days don't always "do" for the kids as they did 10 years ago. If your child makes twice the work for the steward, tip double!!
It's just basic common sense!