Five Stainless Steel Screws Standing at the balcony of my apartment, I can see from a long distance a huge modern steel construction, the Olympic Sightseeing Tower. When the air quality in Beijing is good enough, the Tower can be clearly seen, but if the PM 2.5 pollution index is high, it will be hidden in a heavy smog. So I can determine whether the air is suitable for outdoor activities with a glance at the Tower. An ironic skill, isn't it? The Tower is composed of five individual screw-like structures, and the local people would love to call it by the nickname "Five Screws" ("五颗螺丝钉"). It is quite vivid. Whenever we ask my 15-month-old son Armand, "where are the screws?" he always points out to the balcony with his little hand. This afternoon I received a package. As I pulled the case apart, Armand was very curious about a couple of screws detached from it. "These are screws," I explained to him. As soon as he heard that, he looked out of the balcony with a confused look on his face.