(NewsNation) — An Arizona teacher is making national headlines after he left his teaching career of more than a decade because he couldn’t keep up with his students’ cell phone use.

Mitchell Rutherford taught biology at a high school in Tucson. He told NewsNation that he noticed a shift in his students’ attention span getting worse after the pandemic, with many students even refusing to put away their phones. Some even said that they didn’t care about their grades.

“It’s a big deal,” he said. “It’s hard for every teacher, and all of them continue to tell me that this is the number one problem that we need to fix. Everything else might flow from that.”

About 97% of teens say they use their phones during the school day, according to a study. Researchers say smartphone addiction has negative impacts on students’ learning and overall academic performance. It can also lead to poor sleep quality, attention deficit issues and deteriorating personal relationships.

“It’s hard to see because the kids are struggling in a way that they lacked control over because of how addictive these devices have been intentionally designed to be,” Rutherford said.

Rutherford, however, didn’t immediately give up. He said he tried just about everything.

“For the entire second quarter, we did a sleep study where I educated the students on good sleep hygiene all around including technology, mitigation and trying to reduce phone usage,” Rutherford said. “So they would track their sleep every day. And then they would try and establish good nighttime routines and morning routines.”

Rutherford didn’t stop there.

“I would take the kids out on nature walks where phones stayed in the classroom, and sometimes it was silent. And sometimes they would interact with each other,” he said. “It’s not just a problem in schools, it’s a problem at home.”