This article by Nellie Bowles appeared in the New York Times.

SAN FRANCISCO — Silicon Valley parents are increasingly obsessed with keeping their children away from screens. Even a little screen time can be so deeply addictive, some parents believe, that it’s best if a child neither touches nor sees any of these glittering rectangles. These particular parents, after all, deeply understand their allure.

But it’s very hard for a working adult in the 21st century to live at home without looking at a phone. And so, as with many aspirations and ideals, it’s easier to hire someone to do this.

Enter the Silicon Valley nanny, who each day returns to the time before screens.

“Usually a day consists of me being allowed to take them to the park, introduce them to card games,” said Jordin Altmann, 24, a nanny in San Jose, of her charges. “Board games are huge.”

“Almost every parent I work for is very strong about the child not having any technical experience at all,” Ms. Altmann said. “In the last two years, it’s become a very big deal.”

From Cupertino to San Francisco, a growing consensus has emerged that screen time is bad for kids. It follows that these parents are now asking nannies to keep phones, tablets, computers and TVs off and hidden at all times. Some are even producing no-phone contracts, which guarantee zero unauthorized screen exposure, for their nannies to sign.

The fear of screens has reached the level of panic in Silicon Valley. Vigilantes now post photos to parenting message boards of possible nannies using cellphones near children. Which is to say, the very people building these glowing hyper-stimulating portals have become increasingly terrified of them. And it has put their nannies in a strange position.

“In the last year everything has changed,” said Shannon Zimmerman, a nanny in San Jose who works for families that ban screen time. “Parents are now much more aware of the tech they’re giving their kids. Now it’s like, ‘Oh no, reel it back, reel it back.’ Now the parents will say ‘No screen time at all.’”

Ms. Zimmerman likes these new rules, which she said harken back to a time when kids behaved better and knew how to play outside.

Parents, though, find the rules harder to follow themselves, Ms. Zimmerman said.

The Nanny Contracts

Parents are now asking nannies to sign stringent “no-phone use contracts,” according to nannying agencies across the region.

“The people who are closest to tech are the most strict about it at home,” said Lynn Perkins, the C.E.O. of UrbanSitter, which she says has 500,000 sitters in the network throughout the United States. “We see that trend with our nannies very clearly.”

The phone contracts basically stipulate that a nanny must agree not to use any screen, for any purpose, in front of the child. Often there is a caveat that the nanny may take calls from the parent. “We do a lot of these phone contracts now,” Ms. Perkins said.

“We’re writing work agreements up in a different way to cover screen and tech use,” said Julie Swales, who runs the Elizabeth Rose Agency, a high-end firm that staffs nannies and house managers for families in the region. “Typically now, the nanny is not allowed to use her phone for any private use.”

This can be tricky. These same parents often want updates through the day.

“If the mom does call and the nanny picks up, it’s, ‘Well what are you doing that you can be on your phone?’” Ms. Swales said. “Damned if you do, damned if you don’t.”

She said that at least wealthy tech executives know what they want — no phones at all. The harder families to staff are those that are still unsure how to handle tech.

“It’s almost safer to some degree in those houses because they know what they’re dealing with,” she said, “as opposed to other families who are still trying to muddle their way in tech.”

Narcing Out Nannies

Some parents in Silicon Valley are embracing a more aggressive approach. While their offices are churning out gadgets and apps, the nearby parks are full of phone spies. These hobbyists take it upon themselves to monitor and alert the flock. There are nannies who may be pushing a swing with one hand and texting with the other, or inadvertently exposing a toddler to a TV through a shop window.

“The nanny spotters, the nanny spies,” said Ms. Perkins, the UrbanSitter C.E.O. “They’re self-appointed, but at least every day there’s a post in one of the forums.”

The posts follow a pattern: A parent will take a photo of a child accompanied by an adult who is perceived to be not paying enough attention, upload it to one of the private social networks like San Francisco’s Main Street Mamas, home to thousands of members, and ask: “Is this your nanny?”

She calls the practice “nanny-outing.”

“What I’ll see is, ‘Did anyone have a daughter with a red bow in Dolores Park? Your nanny was on her phone not paying attention,’” Ms. Perkins said.

The forums, where parents post questions and buy and sell baby gear, are now reckoning with public shaming and privacy issues. Main Street Mamas has recently banned photos from being included in these ‘nanny spotted’ posts, Ms. Perkins said.

“We follow and are part of quite a large number of social media groups around the Bay Area, and we’ve had families scout out nannies at parks,” said Syma Latif, who runs Bay Area Sitters, which has about 200 nannies in rotation. “It’ll be like, ‘Is this your nanny? She’s texting and the child is on the swing.’”

Sometimes a parent will step in to defend the nanny and declare that the phone use at that moment was allowed.

“They’ll say, ‘Actually it was my nanny, and she was texting me but thank you for the heads up,’” Ms. Latif said. “Of course it’s very, very offensive on a human rights level. You’re being tracked and monitored and put on social media. But I do think it comes from a genuine concern.”

Commenters will jump in to defend someone — or to point out that no one can be sure whether the perpetrator is a parent or a nanny. The standards are different.

“There is this thought that the moms can be on their phones,” Ms. Latif said. “They can be texting, because it’s their child.”

Others say it shouldn’t make a difference.

Anita Castro, 51, has been a nanny in Silicon Valley for 12 years. She says she knows she works in homes that have cameras set up to film her. She thinks the nanny outing posts cross a line and feel like “an invasion.”

“I use the forums to find jobs, but now just reading the titles: ‘I saw your nanny…’” Ms. Castro said. “Who are these people? Are they the neighbors? Are they friends?”

A few weeks ago at the Los Altos library, another nanny told Ms. Castro about quitting after one mom followed her around parks to snoop.

“She’d pop up and say, ‘Hey, you’re not on your phone, are you? You’re not letting him do that, are you?” Ms. Castro recalled. “So she finally just said, ‘You know, I don’t think you need a nanny.’”