A blackboard, with multiple colors of chalk

A blackboard or chalkboard is a reusable writing surface on which text or drawings are made with chalk or other erasable markers. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. a chalkboard File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... a chalkboard File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Writing may refer to two activities: the inscribing of characters on a medium, with the intention of forming words and other constructs that represent language or record information, and the creation of material to be conveyed through written language. ... The Needles, part of the extensive Southern England Chalk Formation Chalk is a soft, white, porous form of limestone composed of the mineral calcium carbonate. ... Alternate meanings in Slate (disambiguation) Slate Slate is a fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed (foliated) in layers (bedded deposits). ...

A blackboard can simply be a piece of board painted with matte dark paint (usually dark green or black). It is usually dark green as this is less harsh on the eyes than black. A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. Matte can take on one of at least two distinct meanings. ... For information on the U.S. borough, see Paint, Pennsylvania. ...

Blackboard Chalk

Blackboards are commonly used in teaching. The chalk marks can be quickly and easily wiped off with a damp cloth, or a special blackboard eraser consisting of a block of wood covered by a felt pad. Chalkmarks made on some types of wet blackboard can be difficult to remove. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... In education, teachers are those who teach students or pupils, often a course of study or a practical skill. ...

Sticks of processed "chalk" are made especially for use with blackboards, in white and also in various colours. These are not actually made from chalk rock, but from gypsum. Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ... Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. // Chemical structure Gypsum from New South Wales, Australia Heating gypsum above approximately 150°C (302°F) partially dehydrates the mineral by driving off exactly 75% of the water contained in its chemical structure. ...

Blackboards have disadvantages: they produce a fair amount of dust, depending on the quality of chalk used. Some people find this uncomfortable, or may be allergic to it, and there has been speculation about links between chalk dust and respiratory problems. However, other methods of displaying information are more expensive and have drawbacks of their own. These disadvantages have led to the widespread adoption of the whiteboard, which uses ink markers that produce no dust. This article needs cleanup. ... Respiration is the process of exchanging oxygen and carbon dioxide between an organism and its external environment (breathing). ... A small whiteboard with pen and eraser clipped to top A whiteboard is the name for any plastic glossy surface, most commonly coloured white, where markings can be made. ...

The scratching of fingernails on a blackboard is a sound that is well-known for being extremely irritating. This article discusses the anatomical nail. ...

Blackboard Inc. is also the name of an e-learning software company. Blackboard Inc. ... Typical Managed Learning Environment with a navigation menu and online community building tools. ...