If, after a reasonably relaxing six-and-a-half hour sleep cycle, you nearly die on the highway on the way to work because 1) somebody parked their car in a really shitty place on an offramp and oh also 2) you’re honestly fighting falling asleep for basically the entire drive, and then you get to work and, bleary-eyed and brainless, try to open your classroom door with your keycard badge, which, uh, doesn’t work on those kinds of doors, just go home. The day is not going to get better.
I also screwed up solving a problem on the whiteboard for my first hour class, only not only could I not find my error, neither could the entire class, and we sat and stared at it as a group for probably ten minutes. Turns out that, while 1.5 is half of three, that doesn’t mean that 3/1.5 equals 1/2! It equals two.
One grown adult, fifteen honors students, and it took me until lunchtime to figure out what I’d done wrong. I definitely should have given up and gone home after first hour.