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Most American students are on summer break right now, and some school resource officers are preparing for the year ahead. There are more than 14,000 such officers in the country. Mass shootings at schools have renewed interest in their role. Bree Zender from member station KUNR in Reno, Nev., reports on how officers are trying to make schools safer.

BREE ZENDER, BYLINE: About 40 police officers are gathered in this casino ballroom - some brand-new to serving in schools and some veterans. They're taking this class from Officer Seth Sullivan on how to interpret social media posts in the age of mass shootings.

SETH SULLIVAN: You got a kid that has picture of a shotgun on his Facebook or his Instagram, is that necessarily a threat?

ZENDER: Sullivan explains popular and upcoming apps, and which ones are used as tools for bullying. Among the people in this class is Kristi Muilenburg. She's about to start a job as a school resource officer in Palmer, Ala. - population 7,000. She's attending the National Association of School Resource Officers Conference to help her become the district's very first school officer.

KRISTI MUILENBURG: People originally thought, this can't happen to me. And then, the more and more we see shootings happen around the country, there seems to be no real rhyme or reason to it.

ZENDER: While school shootings have been making headlines for decades, the more high-profile ones in the past year or so led her city to want to be more proactive. One important move, hiring a school resource officer, or SRO.

MUILENBURG: They want to have that added protection for the kids to have an SRO there full-time. That's what the city of Palmer feels.

ZENDER: This association putting on this training for 1,000 officers is non-partisan and often shies away from talking about guns. But it did put out a statement in the past year saying it's not in favor of arming teachers.

The group's president, Don Bridges, is a school officer himself, serving in Baltimore County Schools. He says building positive relationships with students can ultimately protect them.

DON BRIDGES: No matter how good your memory is, you don't recognize every student. The kids would oftentimes walk down the hall, and they would pass by you, and they would say, Officer Bridges, that kid with the green coat on, he doesn't go to school here.

ZENDER: For Bridges, trust leads to tips.

BRIDGES: I will never ever divulge where that information came from, even if it means losing a criminal case. I would rather lose a criminal case than to lose the confidence and the respect that that student has for, like, me as an officer.

MARILYN LEWIS: It's relationships that are going to support any incident that happens within schools.

ZENDER: That's Marilyn Lewis. She's an Alabama Board of Education member and a former teacher. Nationwide, about 20 percent of schools have school resource officers in them. That number is slightly higher with Alabama public schools.

Lewis says that stronger presence proved crucial back in March. That's when a shooting at a high school in Birmingham left one student dead. But Lewis says it could've been much worse without their school resource officer present.

Despite all the work that's been done in her state, she says there's much more to accomplish before she can worry less.

LEWIS: Not to say that an incident will not happen in Alabama. However, I think that we will mitigate the situation a whole lot faster because of all of the things that we've put in place to get on the prevention side.

ZENDER: Lewis says investing in safety helps teachers focus on what they're actually there to do - teach. For NPR News, I'm Bree Zender, in Reno, Nev.

(SOUNDBITE OF FLEVANS' "A DISTANT VIEW") Transcript provided by NPR, Copyright NPR.

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