‘White lives matter’ stickers were placed outside their school. These students responded with love.

Randal Green was aghast this week when he saw the sticker stuck to a trash can near J.S. Jenks Academy of Arts and Sciences, a public school in Chestnut Hill.

“White Lives Matter,” it read. “Rise White Man. Preserve Posterity.”

Green — part of a group of Jenks Dads on Duty, fathers, grandfathers, and brothers who volunteer daily directing traffic, escorting students, and generally keeping things safe at the school every morning — felt fear.

“That kind of mentality, that sort of thinking, that sort of language, it’s scary to me,” said Green, father of a Jenks fourth grader. “That’s the kind of thing the guy who shot up the supermarket in Buffalo said. That was sitting in my gut all day.”

White Lives Matter is characterized by the Southern Poverty Law Center as a hate group, “a racist response to the civil rights movement Black Lives Matter” and “a neo-Nazi group that is growing into a movement as more and more white supremacist groups take up its slogans and tactics.”

Green saw a line of stickers — affixed to a nearby parking meter, on a trash can, on stoplights and light poles, all within close range of the school on Germantown Avenue. Alarmed, he approached Jenks principal Corinne Scioli, who quickly alerted the Philadelphia School District and city police.

Philadelphia police confirmed an investigation is underway.

Scioli was alarmed, too, but determined to turn “a message of divisiveness” into a teaching moment.

Something traumatizing happened, but “it’s all about how we respond,” Scioli said. “Through every challenge, there’s an opportunity for growth and knowledge.”

The principal notified the Jenks community, and directed teachers to talk about the incident in a developmentally appropriate way — the youngest students talked about friendship and love, and how it made them feel when people said unkind things. Older students took a more direct path.

Then, under the staff’s direction, students chose to counterprogram in a very public way.

“We decided to respond with love,” said Lauren Thomas, a Jenks eighth grader.

“Negative words can lead to more negativity,” said Leanni Miller-Allen, her classmate. “We wanted positivity.”

Students and staff assembled bags of chalk. On sidewalks around the school, on the Jenks playground — which is widely used by the community when school is not in session — students spent time after school Thursday and before school Friday drawing hearts and writing messages they felt represented their school much better than “White Lives Matter.”

“Love,” they wrote. “Please Stop Co-Opting Blackness.” “Black Lives Matter.” “Get Hate Out of the Equation.”

Gabriella Alexander thought about the stickers — who took the time to display them and why?

“Putting up something like that in the community, that’s not OK,” said Alexander, another eighth grader.

But Alexander and her classmates agreed that what they’ll remember more is the part where they came together to do better.

And the Chestnut Hill community has embraced it. Students and staff left plastic bags of chalk on the sidewalk for passersby to add their own messages.

At midmorning Friday, a preschooler drew hearts on the Germantown Avenue sidewalk while a parent watched.

After school, staff from Philly Children’s Movement, a racial-justice organization that works with educators and community groups, came to the Jenks playground to support families and further discussions.