The whiteboard (also known as whiteboard ) is a reusable writing surface where text or images are created with a calcium sulfate or calcium carbonate stick, known, when used for this purpose, as chalk. The blackboard is originally made from thin and smooth sheets of dark gray or dark gray stone.
Video Blackboard
Design
Whiteboard can be a board painted with matte black paint (usually black, sometimes dark green). The matte black plastic sign material (known as the 'PVC foamboard enclosed cell') is also used to create special whiteboard art. A more modern variation consists of rolled plastic sheets on two parallel rolls, which can be scrolled to create additional writing space while storing what has been written. The highest grade chalkboard is made of coarse porcelain steel (black, green, blue or sometimes other colors). Porcelain is very hard to wear and whiteboard made of porcelain usually lasts 10-20 years in intensive use.
The blackboard whiteboard began in the 1840s. Green boards, generally made of porcelain enamels on steel bases, first appeared in the 1960s.
The college theater can contain a number of whiteboards in a grid setting. The lecturer then moves the board into the range to write and then moves it out of range, allowing a large amount of material to be displayed simultaneously.
The chalk marks can be easily removed with a wet cloth, a special whiteboard sponge or eraser usually consisting of a wooden beam covered by a pad. However, chalk marks made on some types of wet boards can be difficult to remove. Manufacturers of whiteboards often suggest that new or new whiteboards appear completely covered using the side of a chalk stick and then the chalk is brushed as usual to prepare it for use.
Maps Blackboard
Lime attached
The sticks of 'lime' are produced primarily for use with white whiteboards and also in various colors. White lime sticks are made primarily of calcium carbonate derived from lime minerals or lime, while colored or pastel chalk is made of calcium sulphate in the form of dihydrate, CaSO 4 Ã, Â · 2H 2 O, derived from gypsum. Lime sticks containing calcium carbonate usually contain 40-60% of CaCO 3 (calcite).
Advantages and disadvantages
Compared to the blackboard, the blackboard still has many advantages:
- Chalk does not require special care; the whiteboard marker should be closed or they will dry out.
- Lime is an order of magnitude cheaper than a whiteboard marker for a comparable amount of writing.
- It's easier to draw lines with different weights and thicknesses than chalk compared to whiteboard markers.
- The dashed lines can be pulled very quickly using techniques that involve chalk friction (or chalk markers) and whiteboards.
- Lime has a mild odor, while blackboard markers often have a strong odor.
- The chalk writing often provides better contrast than the whiteboard marker.
- Chalk can be easily erased; writing that has been left on the board for a long time may require the solvent to be removed.
- Chalk can be easily removed from most clothing; whiteboard markers often permanently stain fabric, wood (wooden frame), etc.
- Lime is mostly biodegradable, whereas most plastic recyclers will not use whiteboard markers.
On the other hand, lime produces dust, the amount depending on the quality of lime used. Some people find this uncomfortable or may be allergic to it, and according to the American Academy of Allergy, Asthma and Immunology (AAAAI), there is a connection between lime dust and allergies and asthma problems. Dust also prevents the use of lime in areas divided by dust-sensitive equipment such as computers. The writing on the blackboard is hard to read in the dark. Lime sticks shrink through usage, and are famous for breaking half unless put into stationery designed for lime.
Nail scratches on the board, as well as other sharp objects, especially metal objects on the blackboard, produce sounds that are known to disturb most people. According to a study conducted by Michael Oehler, a professor at the University of Media and Communication in Cologne, Germany, humans "tend to hate" the sound of nails on the board. The findings of this study were presented at the Acoustical Society of America conference and support the previous findings of a 1986 study by Vanderbilt psychologist Randolph Blake and two colleagues found that the nail sound on the blackboard interrupts people even when high-pitched frequencies are removed.. This study produced the 2006 Blake Ig Nobel Prize.
Etymology and history
This writing was used in Indian schools in the 11th century as mentioned in Alberuni Indica ( Date Al-Hind ), written at the beginning of the 11th century:
They use black tablets for kids at school, and write them along the long side, not on the wide side, writing with white material from left to right.
The first classroom used a large blackboard that was difficult to date, but was used for music education and composition in Europe as far back as the sixteenth century. The term 'whiteboard' was proved in English from the mid-eighteenth century; The Oxford English Dictionary gives a quote from 1739, to write "with Lime on the blackboard". The first use of lime was proven on the blackboard in the United States from 21 September 1801, in a mathematics course given by George Baron. James Pillans has been credited with the discovery of colored limestone (1814): it has a recipe with ground chalk, dye and porridge.
See also
- Blackboard Jungle
- Chalkboard gag from The Simpsons
- Chalkzone
- Conic Sections Rebellion, an 1830 student rebellion when Yale students were asked to draw their own diagrams on the chalkboard
- limestone sidewalks
- Slate
- The nail sound scratches the whiteboard
- Whiteboard
- Simon in the Land of Chalk Drawings
- Tacita Dean, an artist who often uses blackboards in his work
Note
Further reading
- 'The Blackboard: An Indispensable Necessity', pages 21-34 in the American Mathematical Teaching Tool, 1800-2000. By Peggy Aldrich Kidwell, Amy Ackerberg-Hastings, and David Lindsay Roberts, Johns Hopkins University Press, Baltimore, 2008, ISBN 978-0-8018-8814-4. review
- Ansell, Ben W. (2010). From Voice Mail to Blackboard: The Redistributive Political Economy of Education . New York City: Cambridge University Press. ISBN: 9781107616998. OCLCÃ, 876849496. Ã,
- Whitney, Frederick. 1908 Chalkboard
Source of the article : Wikipedia
0 Comments