Watching Kids by Satellite

It's not just for those under house arrest anymore: Thanks to Wherify, anxious parents can track their children using satellite technology. Wherify's chunky plastic wristwatches, which lock onto a child's arm, are fitted with a Global Positioning System (GPS).

Marketed as a gadget to thwart kidnappings, it is more likely to appeal to the parent of an unruly or latchkey child. Wondering what Michael is up to? The Wherify Web site provides a satellite image of his location. Wonder where he's been? Click on the "Bread Crumbs" option and see his path superimposed on a street map. On the market for over a year, Wherify has sold thousands of bracelets, says Bob Stern, the company spokesman.

When PT's testers took it for a spin, many staffers were appalled by the idea of Big Brother parenting. None of them, however, had kids. Show the gadget to a hardworking, single parent of two active boys, and you've got a potential customer.

PT testers found Wherify had a lot of kinks. Although the company warned that the "urban canyon" of New York City could disrupt the signal, Wherify easily tracked a PT intern to his apartment. But once he was inside, Wherify lost him. It was also thrown off by a taxi ride and failed to find an 11-year-old day-camper in the suburbs. Although the camper thought Wherify sounded "pretty cool," he wasn't keen on wearing it in front of his friends. However, his mother, a single parent, thought the idea was great.

How will this affect parent-child dynamics? Nathan Fox, a professor of child development at the University of Maryland in College Park, thinks Wherify wouldn't erode family relationships. The danger, he says, is that it could replace other forms of parental supervision.