When the Keller kids — Nathaniel, 9, Celeste, 13, and Hayden, 16 — go away to summer camp in Maine, their mom, Amanda Aronoff, worries about them.

But not enough that she'd want them to break the cellphone ban. Implemented by 90 percent of camps accredited by the American Camp Association, rules prohibiting tech allow kids to relearn the art of screenless living.

"They learn independence and have a chance to negotiate social situations on their own,"  insisted Aronoff, of Queen Village. "If they could text me every time they were upset, that would obviously change that scenario."

In fact, without phones, kids' brains change. In a 2014 study by child development expert Yalda T. Uhls of Common Sense Media, preteens who spent just five days at a sleepaway nature camp without access to screens developed a greater understanding of real-world interpersonal communication cues. The campers were better at reading facial expressions, making eye contact, and interpreting tone of voice and other prompts, such as posture and keeping an appropriate spatial distance with others.

But as kids are used to spending more waking hours with a screen than doing any other activity — about two hours and 15 minutes for kids 8 and younger, six hours for tweens, and nine hours for teens — camp without a smartphone remains a challenge.

Kids and parents have had to flex old muscles of independence. Camp administrators have learned to hone the rules and repercussions of cellphone bans (families have implemented creative ways to smuggle in devices). So, as we enter the season of camp registration, we thought we'd ask: How's everyone been faring?

Going tech-free for camp was hard the summer after Isabela Alvarez finally got her own phone — but not as difficult as the following year at Appel Farm Music and Arts Camp in Elmer, N.J. She was in middle school, said Alvarez, now 21, a student at the University of Pennsylvania. "Twitter and Instant Messenger were popular, and that disconnect from the outside world was something I had to get used to."

Upon reflection, Alvarez thinks going tech-free forced her to make friends. "I'm a shy person, so even today, I feel I have the protection of my cellphone if I don't want to participate."

Making new friends will happen more easily without devices, said Mickey Black, owner of Pine Forest Camp, Lake Owego Camp, and Camp Timber Tops, all in the Pocono Mountains.

"It's a simpler life, a little bubble from the world for that time," he said.

Still,  most campers are initially anxious without their devices, said Tom Rosenberg, president and CEO of the American Camp Association, but once they get involved in the activities and camp community, they get through their withdrawal rather quickly.

The biggest culprits are the parents, he insisted. "Part of going to camp is learning how to solve problems with your friends and your counselors, but also learning to manage yourself better."

Despite often being forced to sign a pledge, parents and campers find ways to subvert the rules  — like the night at the International Sports Training Camp in Stroudsburg, Pa.,  when  a camper's teddy bear began vibrating.

"When we catch them with the phone, we confiscate it," said Mark Major, camp director. The parents must then pay $25 to get the phone back, a fine the camp donates to charity. Several years ago, that added up to a $400 donation, but last year only $50.

"There's a very interesting paradigm shift that's happening now," said Major, whose camp has never allowed technology throughout its 25-year existence. "Ten to 15 years ago, parents used to send their kids with two cellphones, so when we found one they would still have a backup. Now, the parents are on our side."

Instead, it's the parent liaisons who get the calls: Parents cut off from their kids can speak to an administrator to hear the details about their happiness, their allergies, their shampoo supply.

Or, they can witness it themselves. In an ironic twist of technology, the fears Serena Gibson of South Philadelphia felt knowing she wouldn't be allowed to call her daughter when she first went to camp at age 7 were quelled when she saw videos posted by the camp on Facebook that showed Tayana was having fun.

Other parents, too, have learned to go with the flow.

"There are definitely times I wish could pick up the phone and say, 'How are you? I miss you,'" Cristy Michaels of Bella Vista said about when her kids, Georgia, 11, and Marina, 8, go to camp. "But it's definitely better not to do that. You're sending your kid to get a sense of self, independence, and autonomy."

A device-free experience encourages campers to be present, practice human interaction, and enjoy the great outdoors — skills sorely lacking among Gen Zers (those born between 1995 and 2012), said Rosenberg. Living without phones also cultivates a feeling of safety and privacy; kids might post pictures of their peers without consent.

"It's an intimate living situation, so if there were a way to take a picture and post it … It corrupts the whole trust that summer camp is built on," said Black.

In the end, nobody knows whether screen time is harmful for kids, said Katherine Dahlsgaard, director of the anxiety behaviors clinic at Children's Hospital of Philadelphia. "But kids deserve a break from all the things screen time entails — sitting still, being passive, not getting fresh air, sunshine, or vitamin D. It's useful for kids to change up their routines and learn new skills."

At camp, kids learn how to entertain themselves when there aren't screens around, which, Dahlsgaard said, is one of the crucial developmental achievements of childhood.

George Tadross misses his 11-year-old daughter, Noelle, when she's away for weeks at a time. But if not getting to talk to her means she'll be able to make real connections with her friends — "as opposed to modern-day play dates where they're all just sitting around playing on different devices" — he's supportive.

There are other benefits: handwritten letters. There was one camp Noelle attended where parents would type letters on the camp website that would be printed out for kids.

"Though it is faster, it's just not the same as sending and receiving a good, old-fashioned letter," Tadross said. Perhaps the analog approach has taken hold: He just learned Noelle saved all the written letters she received, and none of the typed ones.