For exercising minds in a fun way, Mindbenders works like no other. Each book is filled with puzzles that can be solved by using logic and the given clues, and is accompanied by a table to help the student keep track of each new deduction. The twelve books are arranged into three categories, A, B, and C, where level A is easier than level B and level B is easier than level C. Within each level, the four books are numbered with the easiest one coming first and so on, as might be expected.
I often do the puzzles in these books for fun in my spare time. It's an awesome opportunity to use logic without feeling pressured - and there's also the satisfaction of finishing each puzzle! For more information about the books, see the Mindbenders website.