Ever heard of paper and pencil?

Well, yes. But chalk boards seem so much more fun. I remember when I was in school all anybody ever wanted to do was sneak in some time writing on the chalk board.

Probably because it was the "forbidden fruit" of things to do at school. You don't do it unless you are invited.
My kids seem pretty thrilled with it. For some reason it's very satisfying, that scraping of chalk against board. It's a good thing.