Before the invention of the text, it was found that charcoal can be painted. In some ancient caves in Europe, some ancient murals can be found. The walls of these murals can be called blackboards in the traditional sense.
Ancient Chinese teaching used an item called sand table, which was repeatedly written on sand with hardwood, but because of the softness of sand, it could not be considered as a blackboard.
In the Middle Ages, it was found that lime was mixed with water to form a block, which was written on the surface of dark and hard objects in a manner similar to a charcoal pen. In the 19th century, black paint was applied to the surface of the board to protect the board from erosion. Of course, the main role of the blackboard at that time was not teaching, until the mid-19th century, it was popular in schools around the world.
For more than two hundred years, the blackboard has been painted from the earliest black paint on the surface of hard objects such as wood boards and cement, to the water-milled glass in the 1990s, painted steel plates, and composite plates.... Witnessed the step of the world education industry. Development, for the dissemination of knowledge and universal education for human beings, made a great contribution. The types of blackboards are beginning to become more complex and diverse. There are blackboards, green boards, and white boards from the color.... There are plane plates and arc panels from the surface shape, and there are bracket movable plates and push-pull plates from the structure. , lifting board, magnetic blackboard, from the use of teaching blackboard, office whiteboard, advertising board, display board.. and teaching blackboard and electronic blackboard, multi-functional combination board, combined push-pull blackboard, interactive whiteboard, with screen projection Board and so on.