Blackboard ‘chalk’ are produced especially for use with blackboards in white and also in various colours. White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO·2HO, derived from gypsum. Chalk sticks containing calcium carbonate typically contain 40–60% of CaCO (calcite). As compared to whiteboards, blackboards still have a variety of advantages: On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and according
Chalk talk Chalk talk A chalk talk is a monologue presentation done while the speaker draws. It is usually done with chalk, hard crayon, or pastel, or with dry-erase markers on a whiteboard. The chalk talk method of teaching focuses on the blackboard and the lecturer's voice and also the activities – to be precise, the physical activities. This method can be preferred for presenting lectures and talks. Because of an article in the "Deseret News" published on September 17, 1895 the roots of "chalk talks" can be traced to the Methodist church - and a singular individual - Mr. Frank Beard