Not an explantion, but I do remember when they first arrived (there was one the year I began high school -- new physics teacher got to set it up how he wanted)

Not an explantion, but I do remember when they first arrived (there was one the year I began high school -- new physics teacher got to set it up how he wanted) and no new ones when I left. I also saw then appear at MIT, again, mainly new construction/renovation. Chalk boards came in black or green. That name is lost in history, to me. Whiteboards were kind of a shock by comparison -- bright rather than dark -- so it did seem natural. "Marker board" sounds funny now, though it makes sense ("not chalk") but I suppose had it caught on it would be normal. I've only seen "dry erase" used on packages so I assume it's a branding issue. While the one at my HS was the first one I'd seen (and, seemingly the first any of my classmates had seen, as it was a minor topic of dicussion) I think we'd at least heard of them. This was 1978.