Most of us recognize the common chalkboard from school, even that terrible screeching sound it might make upon occasion. It turns out that sound, and other sounds we would call unpleasant have their basis in science, in particular the nature of the human auditory system. The ear and its ancillary nerve structure is designed to amplify sounds with frequencies of 2000-4000 hertz, and this amplification seems to give rise to this negative sensation. The reasons why this is so are not fully understood but might be related to the fight or flight response to imminent danger to ourselves or others.
Anyway, where was I? Oh yes the chalkboard in the office or classroom. Many of these boards have been replaced by “magic” markers and whiteboards. Yet there is something time-honored about a teacher using a blackboard as the visual aid of the day. In the world of mathematics, professors often prefer chalk against the blackboard. Indeed watching a skilled mathematician construct a complex proof is nothing short of a work of art, and there is a need to stand and admire the beauty composed in symbols and logic.
I had a math teacher who liked to show off by holding a piece of chalk in each hand and writing his proofs as mirror images of each other, left hand moving left, right hand moving right. I mention this parlor trick because this same professor would roam around the lecture hall and stop speaking mid-sentence as he gazed out the window. He would pause for an unnaturally long time, so long in fact that we would begin glancing at one another in bewilderment and concern. Then he would start right back up and complete the sentence. We suspected that he was not fully human, but was capable of mimicking one quite well.
It is interesting this fanciful thing called a blackboard. Simple slate and chalk, like modern cave drawings, passing down knowledge one to the next.
whoisfenton 