Parents who have looked up "human body" in the encyclopedia may remember an illustration of each body system that could be added or subtracted layer by layer, peeling back skin, muscles, and organs until all that was left was a skeleton. VISIBLEBODY.COM is high-tech, 3-D update of this human body model created for teachers, students, and medical practitioners. Users can add and subtract systems and parts or render them transparent. Click on a name in the tree diagram to highlight it on the body, or click on a body part to show its name and place on the tree diagram.

Although the site is more about education than entertainment, its interactive design and 3-D controls make it a livelier model than most anything you'd find in a book. There's a "joystick" that can rotate the body along any axis as well as zoom in and out, so users can get a close-up of how a complex organ like the brain is organized, or use a wide angle to learn the names of the major bones in the skeletal system, for instance.

Students will find it useful for getting a hands-on, bigger picture perspective on anatomy concepts, and scientifically inclined teens and tweens may enjoy trying it out just for fun. One thing that would make the body even better: descriptions of what each part is and how it works.

Note: Visible Body requires Unity Web Player and Adobe Flash Player, both of which can be downloaded for free.