"Good," Ron said, nodding in approval. "That there is the rook," he told her, pointing to another piece on the board. "It can move any number of vacant squares vertically or horizontally. The bishop moves any number of vacant squares in any diagonal direction."
He gestured off to the bishop, then peered off at Hermione again. "And then we've got the knight. Remember anything about when I played the role back in first year?"