The Original Yes & Know® Invisible Ink Trivia Game Books are perfect for on-the-go play - each book contains 36 pages of interesting and interactive learning games, puzzles, trivia and so much more, all in full color! Each book includes a special mess-free Surprize Ink!™ magic reveal pen that snaps into the cover for easy storage - perfect for travel or hours of screen-free quiet-time play anywhere. Portable and engaging fun, the classic Yes & Know books have been updated for today's on-the-go kids and families!