The use of chalk has gradually faded from our classrooms. Years ago, children use slates to learn to read and write.
Majority of the classwork were written on slates. Gradually, slates faded away and gave way to exercise books. Today most people are moving away from the black chalk boards to the white boards.
White boards use dry erase ink which are filled into the markers to enable it write.
They are specifically designed to be wiped easily off non-porous surfaces, specifically white board. It requires the user to put less pressure on the board and is less messy. They are erasable even after writing on white board.