CHALLENGE: Latin Square

WHY IT MAY WORK: Latin square puzzles involve shading in blocks in a grid according to a set of specific rules. In a University of Sydney study, doing difficult Latin square puzzles activated brain regions that hadn’t been activated in participants when they were working on easier versions of the puzzle.

PLAY IT: Shade in exactly seven of the empty squares in this grid so that: (1) there is only one shaded square in each row and in each column, (2) no shaded squares touch each other, even diagonally, and (3) the number of shaded squares bordering on the squares containing figures is equal to the figure in each particular square.