My students are always astonishing.

Student 1 is failing. He came in today to ask me to compute his grade for him. He didn't want me to solve the "hard" problem: Given the quantities p &isin [0,1], H &isin [0,100] (homework) and T &isin [0,100] (test), solve the equation (T+x)p + H(1-p) = 60 for x, the score required on the final exam to obtain a passing grade. No, he wanted me to compute his grade: Tp + H(1-p) (astonishing moment number one).

Student 2 is clueless but not failing. I put a challenging extra credit question on the exam, a question that no one had gotten right in so long that I hadn't actually had to work through it in quite some time. She came by, deeply interested in the solution (astonishing moment number two), and asked me to work it through with her. In an (astonishing) moment that will shine as one of my more embarassing, I myself screwed it up, badly. I recovered, but not without some sweat. I am humbled.