They are hybrids, sharing shelf space with craft kits in museum shops or with science ensembles in toy stores. They're in bookstores as well, these books that double as toys or games or dioramas.
Here's a sampling of some of the year's most impressive multi-functional volumes.
* "Pop-Up Theater Proudly Presents Cinderella," produced by Richard Fowler and David Wood (Kingfisher, $17.95, ages 5 and up) opens up to reveal a three-dimensional stage, complete with a curtain and three different backdrops.
The cardboard characters and props are attached to clear plastic Popsicle sticks that the director uses to manipulate them, either from the sides or the top of the stage. The script is easy to follow, with stage directions clearly spelled out and helpful hints on lighting, props and sound effects. It's a must for future drama majors.
* There's no construction required for "Cinderella." The same cannot be said for Dorling Kindersley's excellent new "Action Pack" series of three kits, "Pyramid," "Night Sky" and "Dinosaur" ($16.95 each, ages 7 and up). In "Pyramid," for example, you punch out pieces of cardboard, push tabs into slots and fold and glue until you get a tabletop model of the Great Pyramid, complete with cut-away section to view the interior.
You also get a board game, a secret message written in hieroglyphics and a hieroglyphics decoder, a flip book that undresses a mummy and a bunch of other cool stuff. These kits will keep kids busy straight through New Year's Day.
* "Wonder House" (Random House, $20, ages 4 and up) is a book and science kit written by Elizabeth M. Fitzgerald, director of The Magic House of the St. Louis Children's Museum. The spiral-bound book doubles as the roof of a house; the foundation is a box complete with balloons, pipe cleaners, magnets, a pipette and tablets of food coloring.
As you flip through the book's 40 experiments, the page on one side of the book spells out directions for kids to follow, and the opposite page gives parents hints on how much they need to help, what questions the experiment might prompt and ideas for related experiments.
* "Make Your Own Museum," by Andrea P. A. Belloli, designed by Keith Godard (Ticknor & Fields, $29.95, ages 4 and up) will teach parents as well as kids plenty about art museums.
It has a 36-page guidebook, three slick cardboard galleries to use as diorama shells and more than 70 works of art from the J. Paul Getty Museum -- punch-out sculptures and furniture as well as Colorforms paintings and masks that can be displayed any which way on the gallery walls. There are also suggestions on creating your own museum collections, of rocks, perhaps, or plastic animals. It'll give you a brand-new perspective on your next trip to the Walters or the BMA.
* "Eye Magic" by Sarah Hewetson, illustrated by Phil Jacobs, paper engineering by Ruth Mawdsley (Artists & Writers Guild Books, $19.95, ages 4 and up) is jam-packed with optical illusions. There's a fun-house mirror, a set of glasses for viewing 3-D art, acetate sheets to show visual vibrations and even a pop-up zoetrope. The zoetrope, a spinning drum that makes a series of images appear to be a moving picture, was a bit too ambitious -- I couldn't get it to fold down flat enough to spin correctly. But the other projects performed as promised.
* As a child, I would mess around with my older brother's magic kit and never get any of the tricks right. Now there's hope for the prestidigitation-impaired: "Master Magician" by Sandy Ransford (Running Press, $19.95, ages 5 and up).
It includes the essentials -- a magic wand, a red silk handkerchief, a vanishing coin box, two trick coins, three foam balls, a dice trick, a deck of cards, a magic rope, three linking rings and a false thumb. Better than the props, however, is the 18-page instruction book. Packed with step-by-step photographs of kids who demonstrate how the tricks are done, it taught even a klutz like me how to make a coin disappear up my sleeve and how to make a six-inch piece of rope grow by a couple of yards.