Question

what is the use of a blackboard?​

Answer 1

Explanation:

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 Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone.

Answer 2

A blackboard (also known as a chalkboard) is a reusable writing surface on which text or drawings are made with sticks of calcium sulfate or calciumcarbonate, known, when used for this purpose, as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone.

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