With first- and second-graders, she presents a picture of opioids, explains that if someone takes too much they can fall asleep and stop breathing, and then shows how to “open, insert, squirt” the Narcan spray, letting each child push the plunger.

For adolescents, the training is as much about destigmatizing drug use as reversing overdoses.

Ms. Barnett often starts lessons by sharing details about her own three-year struggle with opioids. She was a nurse with her own health care clinic when she began abusing prescription opioids, after filing for a divorce and then the untimely death of her husband. Her addiction eventually led to snorting around 50 pills a day, having her clinic raided and a 14-month prison sentence.

Her honesty packs an emotional punch, she said, pointing out that many students have asked her how they can encourage a parent to confront their addiction and focus on recovery. “I’ve never had a child who was offended or scared,” she said of the training. “It’s the adults who think it’s inappropriate.”

Yordi Mendez, 16, grew up surrounded by drug use. At 13, he said he tried cocaine that his father had left in a bathroom, and he has seen two friends die from overdoses. He was caught vaping at school and is among nearly 100 students who since June have received Narcan training because of court-ordered vaping cessation classes, taught by the Carter County Drug Prevention Coalition, the same group Ms. Reece leads.

Learning how to administer Narcan, Yordi said, inspired him to join the coalition’s youth board, whose 35 members range from fourth-grade through high school.

The youth board has come up with an array of strategies for reaching their peers, such as a mental health lending library with books on depression and anxiety. After finding that many children in low-income housing were taking care of their younger siblings, the coalition last March began teaching babysitting seminars that include Narcan training, along with lessons on changing diapers and first aid techniques.

“We’ve had a lot of experience with kids who find it easier to listen to other kids as opposed to adults,” said Jocelyn Marr, 17, the youth board president, who teaches the class and created the murder mystery opioid game.