Why isn't the blackboard green board?
The blackboard is not specific to the black surface. In traditional sense, it is a flat surface that can be written over and over again. The surface is hard and is used for teaching. Made of boards or frosted glass, etc., may be written on a specific writing material, such as chalk. Mostly black, blackish green, white or beige.
Green plate is dark green, chalk, does not irritate the eyes, help protect the eyesight; the whiteboard surface is white, with a variety of water color writing.
