Interesting subject! I really liked the last line.

Funny little bit of pondering. Works pretty well as a metaphor, I thought. Seems to beg for a sequel about how blackboards now feel entirely antiquated with the rising popularity of whiteboards.
Some of the sentences are bit tricky to decipher, especially near the beginning, just on account of complex structure, and I think one is a fragment.

I agree with THX, the beginning is very rough and difficult to follow. But you elaborated on the metaphor well at the end. :)