Why Some Grandmas Almost Always Stay Sharp According to AARP Seniors can "stay sharp with brain fitness games and even improve their memory and retention." Just imagine achieving mental fitness in as little as 7 to 17 minutes a day. These crossword puzzles for grandma are easy and progress in difficulty slowly. With the large format of 8.5 x 11" size, it is the perfect size to accompany her on trips to the doctor, pharmacy or other areas where you must wait in line. If you or your loved one wants or needs to keep their mental sharpness and acuity, you should buy this little gem today.