Once upon a time, I actually saw my teenaged daughter. We had one computer, in a shared family space, and she did her homework and Facebooking there.

Then her school issued her a laptop, and she disappeared. Why hang out with your parents when you can bring the whole digital world into your bedroom?

We live in Lower Merion School District in suburban Philadelphia, which recently made national headlines for allegedly spying on students via webcams installed in school-issued laptops. Like other parents in the district, I'm deeply concerned about the possible invasion of our kids' privacy by school officials.

But I also worry that the laptops give our children too much privacy -- from their own parents and siblings. And that's the issue nobody seems to be addressing right now. Whatever else they do, school-issued laptops encourage kids to retreat into their own lairs. And that can't be good for them, or for their families.

According to a recent study by the Kaiser Family Foundation, 36 percent of American children between the ages of 8 and 18 already have a computer in their bedroom. The rest need to go elsewhere in the house to get on the Net.

With a school-issued computer, however, they won't have to. And we're talking about millions of kids here. In 2006, a study of the nation's 2,500 largest school districts found that one-quarter of the respondents provided "one-to-one computing," as student laptop programs are called. Fully half of the districts expected to have such a program in place by 2011.

Now, perhaps you're the kind of Herculean parent who can prevent an American teenager from taking her laptop to her bedroom. If so, more power to you. But the rest of us aren't that strong. And we see our children less.

That might be an acceptable price to pay if we knew laptop programs actually help kids learn. But here's the plain truth: We don't. For every study demonstrating a slight increase in achievement as a result of one-to-one computing programs, there's another study showing no effect at all.

Most notably, researchers in Texas found no significant difference in state test scores between 21 middle schools that gave students laptops in 2004 and 21 middle schools that didn't.

On surveys, however, students consistently report that laptops enhance learning. And so do school boards, who hold the purse strings. Amid the worst economic downturn since the 1930s, they continue to pour scarce resources into student computing.

Why? Laptop programs reflect a long tradition of gee-whiz technological enthusiasm in American education: to fix the schools, the argument goes, find a new gadget.

The most famous proponent of techno-education was Thomas Edison, who invented motion-picture films and started a company to market them in the schools.

"I believe the motion picture is destined to revolutionize our educational system," Edison predicted in 1922, "and that in a few years it will supplant largely, if not entirely, the use of textbooks."

In the 1930s, similar claims were made for radio; and in the 1950s, for television. And now we invoke computers, the latest technological savior for our educational problems.

Nothing can save education, of course, save the people who actually deliver it: our teachers. But Americans don't trust them. Indeed, the constant search for the next technological fix shows how little faith we place in classroom teachers.

Our young people are paying attention. Over the past four decades, as my colleague Sean Corcoran has shown, a declining fraction of the most talented college graduates have chosen to enter the teaching profession.

There's only one way to reverse that trend, of course, and we all know what it is: to raise teachers' pay and prestige, so the job becomes more attractive to the best students.

That will be expensive and it won't show results overnight. But if we're serious about transforming our schools, we need to think more about investing in people -- not in machines.

Meanwhile, I've resolved to spend more time in my daughter's room. I can't stop her from taking her laptop up there, away from the rest of us. But she can't stop me from following her, either. Stay tuned.

Cartoonist Rob Rogers does "Rob's Rough," an early look at his work and his creative process, exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.