blackboard
n.a large, dark board used in classrooms for writing on with chalk. Teachers use it to show lessons to the whole class.
n.a large, smooth, dark surface, typically made of slate or wood, used in educational settings for writing or drawing with chalk.
“The teacher wrote the homework on the blackboard.”
“After the lecture, the student stayed behind to copy the complex diagrams from the blackboard into her notebook.”
“While many modern classrooms have transitioned to digital displays, the traditional blackboard remains a symbol of academic instruction and manual calculation in many parts of the world.”
Often used as a compound noun; increasingly replaced by 'whiteboard' or 'smartboard' in modern contexts.
From black + board, because such surfaces were once typically made of black slate.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.