History of a blackboard

  • History of a blackboard

    • History of a blackboard room...

    History of a blackboard

  • History of a blackboard
  • History of a blackboard class
  • History of a blackboard room
  • History of blackboard learning system
  • What is the use of blackboard in classroom

    • Blackboard

    Reusable writing surface

    For other uses, see Blackboard (disambiguation).

    "Chalkboard" redirects here. For other uses, see Chalkboard (disambiguation).

    NASA scientist Homer E.

    Newell Jr. explaining principles of altitude, pressure, and temperature, c. 1973

    Other namesChalkboard, writing-board
    UsesReusable writing surface on which text or drawings are made

    A blackboard or a chalkboard is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate 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    Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone.

    Design

    A blackboard can simply be a board painted with a dark mattepaint (usually black, occasionally dark green).[1] Matte black plastic sign material (known as closed-cell PVC foamboard) is also used to create custom chalkboard art.[2] Blackboards on an A-frame are used by restaurants