This year marks my 20th year of university-level teaching.  I first started as a graduate student at the University of Chicago in 1993, and over the years I’ve taught probably close to 100 sections.  Every quarter, for every class, I still get the first-day jitters.  It doesn’t matter if it’s the first time I’m teaching a class or if I’ve taught the class dozens of times.  I get nervous, my heart races, my hands get cold, and I can barely sit still for the hour or so before each class.  It’s diminished over time — it used to last for days, rather than hours, and it no longer lingers past the first week.  But I would have never guessed that it would have persisted this long.