Comment by FiatLuxDave

This discussion reminded me of my best Diff Eq prof. He would start each lecture by putting a small clock on his podium, and starting at the precise time listed for the start of the lecture. Then he would leap into action, chalk dust flying around him as he explained the subject of the day. He would often go through more than six full-size chalkboards, having a student erase a few chalkboards behind him so he could return to use the first chalkboard when he ran out of room on the sixth one. Then at the precise time scheduled for the end of the lecture, he would take the clock off the podium and leave the room.

You could often see him walking around campus, covered in a fine white dust, looking like a ghost.

It's been 30 years, and I couldn't remember his name, but man do I remember his lectures.

Update: after typing this, I searched for him, and unfortunately found him almost immediately. He just passed away, and there was a memorial to him on the front page of his math department: https://www.math.fsu.edu/DepartmentNews/Articles/Fac_Nolder....

I note this line from the memorial: His students marveled at his ability to draw a perfect circle on the blackboard with a single stroke.

Here's to you, Dr. Nolder!