when did they stop using slates in schools
Slate (writing) The exact origins of the writing slate remain unclear. References to its use can be found in the fourteenth century and evidence suggests that it was used in the sixteenth and seventeenth centuries. The central time period for the writing slate, however, “appears to begin in the later eighteenth century, when developments in sea and land transport permitted the gradual expansion of slate quarrying in Wales and the growth of a substantial slate workshop industry.”[4] By the nineteenth century, writing slates were used around the world in nearly every school and were a central part of the slate industry. At the dawn of the twentieth century, writing slates were the primary tool in the classroom for students. In the 1930s (or later) writing slates began to be replaced by more modern methods.[5] However, writing slates did not become obsolete. They are still made in the twenty-first century, though in small quantities.
Slate industry The most significant is that of Cornwall and Devon where the Delabole Quarry is thought to be the largest single quarry in the island. Many of these are no longer worked owing to lower costs of extraction in the larger British workings. The quarrying of slate in Cornwall is known to have been carried out from the late mediaeval period and there was a considerable export trade from some of the quarries near the coasts in the 19th century.