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Projected aids have been used since 1420.
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In 1801, in Scotland, James Pillans, Head of the school and geography teacher, hung a large piece of slate on the wall to teach the students
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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.
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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.
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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 word chalkboard came into use.
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In the US by mid-19th century, every class room had a blackboard to teach students.
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The whiteboards came into use during the late 1980s
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Instead of chalk pencils, whiteboard pens were used to write on whiteboards. Considering the health reasons and cost-effectiveness, by 1990s most of the class rooms were replaced with whiteboards instead of blackboards
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The modern version of the blackboard is either green or brown board. This was introduced in late 1960s.
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In the 20th century, blackboards were mostly porcelain-enameled steel and could last 10 to 20 years.
