Do you remember how fascinating and fun transparency books were?

Especially grizzly, gross, and so, of course, great, were those that showed what lay inside the human body. Those books, with their series of clear pages that overlaid one on top of another--adding the veins, the arteries, the muscles, the internal organs the nervous system--revealed a hidden world to curious kids.

Now there are moving, revolving, 3-D images kids can call up on the family computer, images that are much more accurate and representative. But the act of piling up or peeling away those transparency pages still fascinates young children. There's something about being able to slowly strip away the skin, the muscles, the various systems that work so perfectly together within the body, that remains riveting. It's l…