Today (and every day) I'm thankful for that time Mr. Taft taught me how to shake hands.
When I was in eighth grade, on the first day of school, someone came up with the cute idea of everyone in the middle school's shaking everyone else's hand in the middle school. As an introvert, the idea was a bit overwhelming to me, so I wasn't terribly enthusiastic. When I shook Mr. Taft (my eighth grade U.S. history teacher)'s hand, I pinched his metacarpals (not intentionally), and he said, "Ow!" But then he stopped, and showed me: note the web between your thumb and forefinger. When you shake someone's hand, your web should intersect their web. If you do that, you can squeeze someone's hand as hard as you like, and it will come across as firm, never painful.
A strong handshake is a simple thing, but crucial to success in America. It wasn't part of his lesson plan, but Mr. Taft saw an opportunity to teach me something, and went ahead and did it, and I am thankful.