Invisible Ink Yes & Know 7-77

The special pen reveals the invisibly printed answers. See how much you know with hundreds of interesting questions on dozens of different topics. Have fun competing with the invisible opponent as you play games by yourself. Check out all 6 books in the Yes & Know(c) Invisible Ink Book series. Book Includes: special pen 48 pages of fun games and trivia Ages 7+ Book Size: 6" x 11"