Chalkboard started in 19th century and used in school of medieval England. In the time of Revolutionary War era in colonial America, it was carried by students. The Modern chalkboard was established in 1823 and developed by an Educator Samuel Reed Hall.
A chalkboard or blackboard is a reusable writing surface using a stick of calcium sulfate which we known as chalk. It used for educational purposes but also you can see it in a workplace, at home and also in the restaurants. Porcelain enamel is the common used for the material of chalkboard. There are variety of sizes, styles and colors bu the common are the green and black , although shades of brown, blue and gray are also available. The size of the board as large as 120�¯�¿�½x48 for classroom use; 42�¯�¿�½x25�¯�¿�½ for basketball court; or 72�¯�¿�½ x28�¯�¿�½ for stand alone or a movable boards. The board can be painted with matte dark paint usually a black or green. The blackboard use for teaching and chalk marks can be easily wiped off with damp cloth, a sponge or a special blackboard eraser, a block of wood covered by a felt pad.
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