The answer to the crossword clue "They study how knights move" is most likely SQUIRES. This is a 7-letter word often used in crossword puzzles to refer to those who historically studied or trained knights, relating to the theme of knights and their movement in the game of chess or the medieval context.

Regarding how knights move: In chess, a knight moves in an "L" shape — two squares in one direction (vertical or horizontal) and then one square perpendicular to that. Knights can jump over other pieces and alternate color squares with each move.