Not too many places left in which you actually have blackboards and chalk, but Saturday I found myself giving a workshop amidst the scent of chalk, the residue of chalk, and all the memories it brings even though it’s now usually calcium sulfate or magnesium silicate. Mr. Campbell’s powdery blackboards full of Latin declensions, a drawerful of my dad’s tailor chalk long past the time of his tailoring, and the black asphalt sidewalks of my childhood hopscotch games.