Easy ten lines for blackboard
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it helps teacher for teach the students.....
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The blackboard is a recent innovation. Erasable slates, a cheap but durable substitute for costly paper and ink, had been in use for centuries. Students could practice reading and writing and math on their slates, in the classroom or at home. But it wasn’t until 1800 that James Pillans, headmaster of the Old High School of Edinburgh, Scotland, wanting to offer geography lessons to his students that required larger maps, connected a number of smaller slates into a single grand field. And in 1801, George Baron, a West Point mathematics teacher, also began to use a board of connected slates, the most effective way, he found, to illustrate complex formulas to a larger audience.
Although the term blackboard did not appear until 1815, the use of these cobbled-together slates spread quickly; by 1809, every public school in Philadelphia was using them. Teachers now had a flexible and versatile visual aid, a device that was both textbook and blank page, as well as a laboratory, and most importantly, a point of focus. The blackboard illustrates and is illustrated. Students no longer simply listened to the teacher; they had reason to look up from their desks.
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Like many of the best tools, the blackboard is a simple machine, and in the 19th century, in rural areas particularly, it was often made from scratch, rough pine boards nailed together and covered with a mixture of egg whites and the carbon leavings from charred potatoes. By 1840 blackboards were manufactured commercially, smoothly planed wooden boards coated with a thick, porcelain-based paint. In the 20th century, blackboards were mostly porcelain-enameled steel and could last 10 to 20 years. Imagine that, a classroom machine so durable and flexible. In my daughter’s schools, computers, scads of them, are replaced every two to three years.
While black was long the traditional color for blackboards, a green porcelain surface, first used around 1930, cut down on glare, and as this green surface became more common, the wordchalkboard came into use.
Chalk, of course, predates the blackboard. The chalk with which we write on boards isn’t actual chalk but gypsum, the dihydrate form of calcium sulfate. Gypsum is found naturally and can be used straight out of the ground in big chunks, but it can also be pulverized, colored, and then compressed into cylinders. My most important high school teacher, Mrs. Jouthas, used a variety of neon-colored chalk to help us differentiate the parts of speech, or follow the rhythms of a Mark Twain paragraph.
The last time I saw a real blackboard in a classroom was during a visit to a still-functioning one-room schoolhouse near Hollister, California. The blackboard had been faithfully reconstructed as a souvenir of the school’s past, while the teacher and students mainly used the whiteboards that covered the other walls. Whiteboards are the rule these days, and all to the better, it seems, if only for their lack of screeching. But the whiteboard disallows a long-standing classroom rite: cleaning the erasers.
please choose important points
The blackboard is a recent innovation. Erasable slates, a cheap but durable substitute for costly paper and ink, had been in use for centuries. Students could practice reading and writing and math on their slates, in the classroom or at home. But it wasn’t until 1800 that James Pillans, headmaster of the Old High School of Edinburgh, Scotland, wanting to offer geography lessons to his students that required larger maps, connected a number of smaller slates into a single grand field. And in 1801, George Baron, a West Point mathematics teacher, also began to use a board of connected slates, the most effective way, he found, to illustrate complex formulas to a larger audience.
Although the term blackboard did not appear until 1815, the use of these cobbled-together slates spread quickly; by 1809, every public school in Philadelphia was using them. Teachers now had a flexible and versatile visual aid, a device that was both textbook and blank page, as well as a laboratory, and most importantly, a point of focus. The blackboard illustrates and is illustrated. Students no longer simply listened to the teacher; they had reason to look up from their desks.
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Like many of the best tools, the blackboard is a simple machine, and in the 19th century, in rural areas particularly, it was often made from scratch, rough pine boards nailed together and covered with a mixture of egg whites and the carbon leavings from charred potatoes. By 1840 blackboards were manufactured commercially, smoothly planed wooden boards coated with a thick, porcelain-based paint. In the 20th century, blackboards were mostly porcelain-enameled steel and could last 10 to 20 years. Imagine that, a classroom machine so durable and flexible. In my daughter’s schools, computers, scads of them, are replaced every two to three years.
While black was long the traditional color for blackboards, a green porcelain surface, first used around 1930, cut down on glare, and as this green surface became more common, the wordchalkboard came into use.
Chalk, of course, predates the blackboard. The chalk with which we write on boards isn’t actual chalk but gypsum, the dihydrate form of calcium sulfate. Gypsum is found naturally and can be used straight out of the ground in big chunks, but it can also be pulverized, colored, and then compressed into cylinders. My most important high school teacher, Mrs. Jouthas, used a variety of neon-colored chalk to help us differentiate the parts of speech, or follow the rhythms of a Mark Twain paragraph.
The last time I saw a real blackboard in a classroom was during a visit to a still-functioning one-room schoolhouse near Hollister, California. The blackboard had been faithfully reconstructed as a souvenir of the school’s past, while the teacher and students mainly used the whiteboards that covered the other walls. Whiteboards are the rule these days, and all to the better, it seems, if only for their lack of screeching. But the whiteboard disallows a long-standing classroom rite: cleaning the erasers.
please choose important points
Aarohikhan:
Nice
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