Plural of blackboard; dark boards, traditionally dark-colored, used for writing with chalk in classrooms.
Compound of 'black' and 'board' (Old English 'bord'). The boards were originally made dark to provide contrast with white chalk writing.
Blackboards revolutionized teaching because the dark surface made chalk writing visible from the back of a room—before them, teachers had to rely on reading aloud or showing individual students one at a time.
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