“Before a game of tournament Scrabble, the tiles being used that game are set out on the board, so that people can make sure that none are missing. One typical way of doing this is to make four 5×5 groups of tiles in the corners of the board… Dan Stock has recently determined that it’s possible to use the 100 tiles in a Scrabble set to form four 5×5 word squares where all the entries are Scrabble-legal.” [via jessamyn on twitter]