Blackboard
A blackboard (UK English) or chalkboard (US English) is a reusable writing surface on which text or drawings are made with sticks of calcium sulfate or calcium carbonate, known, when used for this purpose, as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. Modern versions are often green because the color is considered easier on the eyes.
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Famous quotes containing the word blackboard:
“When Wilson got upon his legs in those days he seems to have gone into a sort of trance, with all the peculiar illusions and delusions that belong to a pedagogue gone mashugga. He heard words giving three cheers; he saw them race across a blackboard like Mexicans pursued by the Polizei; he felt them rush up and kiss him.”
—H.L. (Henry Lewis)