Nota histórica: la pizarra

"In the winter of 1813 & 14, during my first college vacations, I attended a mathematical school kept in Boston by the Rev. Francis Xavier Brosius... On entering his room, we were struck at the appearance of an ample black board suspended on the wall, with lumps of chalk on a ledge below, and cloths hanging at either side. I had never heard of such a thing before. There it was—forty-two years ago—that I first saw what now I trust is considered indispensable in every school—the black board—and there that I first witnessed the process of analytical and inductive teaching."

—Samuel J. May, abolitionist, 1855

Picture shows Feynman using blackboards.