Blackboard

A broad board painted black or any black surface on which writing drawing or the working of mathematical problems can be done with chalk or crayons It is much used in schools In late 20th century similar boards of a green slate as well as some colored white became common wrioting on the slate bioards may be done with chalk but writing on the white boards is done with colored pens such as grease pens which leaves a trace that can be easily erased The newer boards usualy called chalkboards are nevertheless still sometimes referred to as blackboards