Answer:
An Americanism dating back to 1935–40; chalk + board
Chalk: before 900; Middle English chalke, Old English cealc < Latin calc- (stem of calx ) lime
Board: before 900; Middle English, Old English bord board, table, shield; cognate with Dutch boord board, bord plate, German Bort, Old Norse borth, Gothic -baurd
The origins of the chalkboard date back to the early decades of the 19th century. The forerunner of the chalkboard was the small, paddle-shaped hornbook. This item had been in use in schools of medieval England, and by the time of the Revolutionary War era in colonial America, it was carried by legions of students.
