Serious bibliophiles know it's always a challenge to fit all your books on the shelf! So we know you'll be a whiz at this clever 3D stacking puzzle, which has you arrange twelve wooden "books"— and one adorable kitty—in different configurations, making sure that the top shelf is evenly balanced (a level is included to check your handiwork). Forty challenge cards—ranging in difficulty from beginner to expert—offer different parameters to stump even the shrewdest of library organizers. For ages 8 and up