Chalk produce, and thus widely used in the developing world, calcium-based chalk can be made where the crumbling particles are larger and thus produce less dust, and is marketed as "dustless chalk". Colored chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often colored), used to draw on sidewalks, streets, and driveways, are primarily made of gypsum. Chalk is a source of quicklime by thermal decomposition, or slaked lime following quenching of quicklime with water. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines,
Chalk talk use of colors and techniques and the approach talks about the easy use of chalk talk with unnecessary details which can be carried out quickly [makes no sense]. People who are not familiar with this method and would like to give this method a try, this is a perfect book to get access to. A chalk talk was a popular act in vaudeville. A performer used chalk on a blackboard to make changes in a drawing while delivering a monologue. Some performers would do caricatures of audience members. The term also was used to describe an act done with crayons.