Book excerpt: Mark Danna knows how to create puzzle challenges that children find irresistible. That s why Word Search Puzzles for Kids, as well as his other collections, sold 149,700 copies. Now, he s serving up his sixth helping of ingeniously designed and wildly imaginative word searches that smart youngsters will snap up. Each fun grid is a picture (not a ho-hum square) based on the puzzle s theme, including one shaped like a unicorn for a Fantastic Creatures search. There are rebuses, too, searches where kids have to make up the word list from clues, and puzzles with extra-special, tricky twists. The icing on the cake: each word search contains a hidden message that youngsters can only decipher after they ve completed the grid. "