Today, how-to books from Klutz come packaged with the tools of their trade (from juggling cubes to face paints to yo-yos), and are designed for doing, not just reading. "We think people learn best through their hands, nose, feet, mouth and ears. Then their eyes. So we design multi-sensory books," Cassidy says. The appeal of this hands-on approach is borne out by sales figures; Klutz is a fixture on U.S. book and toy bestseller lists, and is available in 24 countries around the world.