sentence: Special markers are used that can be erased.
sentences_before: A 'whiteboard', also called a 'markerboard', is a drawing surface on which markings made with markers are visible. It is used as a surface to write on. Whiteboards are often used to help teach.
sentences_after: Whiteboards usually have a shiny surface. Before there were whiteboards,, people used blackboards. Chalk is used to write on blackboards. Now, there is another improvement, people are now using electronic whiteboards, where it is controlled by a computer.
concept_name: special marker
headings: Whiteboard