Whiteboard
Whiteboards became commercially available in the early 1960s, but did not become widely used until 30 years later. Early whiteboards needed to be wiped with a damp cloth and markers had a tendency to leave marks behind, even after erasing the board. Dry-erase markers for whiteboards were invented in 1975.
History of Go
In 1954 a complete Go board made out of stone was found in a tomb dating to the Eastern Han dynasty (25–220) in Wangdu County, Hebei Province. This board has a 17 × 17 grid, which confirms the statement by the 3rd century author Handan Chun in the "Classic of Arts" that Go was at this time played on a 17 × 17 grid:
The go board has 17 lines along its length and breadth, making 289 points in all. The black and white stones each number 150.
The earliest board with a 19 × 19 grid to have been found is a ceramic board dating to the Sui dynasty (581-618) that was excavated from Anyang in Henan Province, so sometime between the 3rd and 6th centuries a change in grid size must have taken place. However, the 17 × 17 board has survived in the version of Go played in Tibet.