Where you sit in class and what it means
This is surprisingly accurate. Having taught for 13 years or so, and most of those in one room, I can predict with surprising accuracy where the distractive talkers will sit, based on hemisphere dominance, saccadic eye movement, and self-selected seating arrangement. I sometimes even make a joke at the start of the semester, walking over and saying, "I've never met you people in my life, but I know you will be cut-up, whisper-chitter slackers. Why do I know this? Because given how you look at things, and given where you're sitting, it's all been determined by the biology of your brain." Sometimes those students (or their acquaintances, not necessarily "friends") will ask did I hear something about them from somebody, because I was sure right about so-n-so. "No," I answer, "It's just that God was kind enough to build in an early warning system about them for the rest of us."