ATLANTA >> In open houses and meet-and greets, teachers across the country will review rules on homework, late assignments and misbehavior. They will also spend time on a major distraction in their classrooms largely created by parents.

Smartphones.

Allowing the magic boxes in classrooms is like setting down a picnic basket on an ant hill. It’s hard to block kids from using their phones to text message, download music or stream video. Parents fight attempts by schools to ban phones because they want their children within immediate reach.

As one high school teacher explained, “I don’t allow students to use their devices in my class since I can’t control what they are accessing — most students don’t connect to school Wi-Fi because it filters what they can access.”

Don’t blame teachers for failing to monitor what kids do on their phones. Parents aren’t adept at it, either.

In a recent Common Sense Media/SurveyMonkey online poll, 44 percent of parents of teenagers cited their child spending too much time on digital devices as their No. 1 concern. But 52 percent felt they were “extremely” or “very” aware of what their teens did online. However, when asked whether they felt their parents were really that aware of what they did, only 31 percent of teens agreed.

A troubling study released this month suggests the fast, high-intensity stimulation provided by smartphones can contribute to mental health issues. After tracking 2,600 teenagers for two years, researchers at the University of Southern California found heavy users of digital devices are twice as likely to show symptoms of attention-deficit/hyperactivity disorder.

Many teachers urge parents to delay giving their child a phone until high school. Unfortunately, research suggests the average age for American children receiving their first smartphone is much younger, around age 10.

Once kids have a phone, a Nielsen Mobile Kids report found their top activity was texting.

“Seeing how quickly my daughters got addicted to them after getting them in eighth grade, I am reluctant to get them for their younger brothers, but I recognize that, as they get older, they are away from home more and need to communicate with us,” said one parent and teacher. “It saddens me that my girls seem satisfied with texting their friends, and don’t ask to go see them on weekends and in the summer. I don’t feel that phones are good for the development of good relationships and communication.”

Another mother said, “I’m apparently in the minority, and my oldest didn’t get his first smartphone until the middle of his sophomore year. He was probably the only kid who didn’t have one.”

If your child has a phone, retrieve it at night. “I can’t tell you how many of my students come in exhausted after having been up the better part of the night texting/Snapchatting/Instagramming friends or just watching hours of YouTube,” said a high school teacher.

A sixth-grade teacher said he suggests three rules to parents:

1. No phones in the room when students are working on homework. This is one way how homework assignments turn into multihour ordeals … just a little time working and lots of time on social media and texting.

2. The phone needs to charge in the parent’s room at night. Kids will hear the phone and will stay up until all hours of the night.

3. Remind kids the phone belongs to you — the parent. If you text or call you expect a response — not to be ignored.