Kindness is a simple thing, a concept nearly everyone understands and one just about nobody opposes. Yet examples of kindness in American society are unusual enough to be often surprising and even newsworthy.

Perhaps the rarity of true kindness owes something to this nation’s capitalist roots, which frequently manifest themselves in the ugliest, least-kind ways possible. Maybe a society focused on selfies finds it inconvenient to turn its focus outward from time to time. It’s possible there’s some correlation between the breakdown of the family unit and the hardening of society.

At the least, it seems likely that kindness is a skill that must be taught. From the time they’re born, most children are concerned primarily with their own desires. Those who are fortunate enough to have parents and extended families that are engaged and devoted to raising empathetic adults come to learn that self involvement makes for a hollow life and hurts the community at large.

Recognizing and attempting to close the kindness gap was one of the primary reasons for The Great Kindness Challenge, a week in January devoted to encouraging students across the nation to perform as many acts of kindness as possible. The hope was that — as with any skill — helping youngsters practice kindness would improve their ability and motivation to be kind to others.

Students at Mack Benn Jr. Elementary School wrote encouraging letters to random students at other schools and contributed to a bulletin board about what kindness means to them. They also received a checklist of kind acts that included things like greeting others in the morning, writing a happy message with sidewalk chalk and donating school supplies.

Those are all small acts of kindness, but again, as with any skill, an aptitude for kindness starts with little things. And, as with any learned behavior, kindness benefits from encouragement.

To help encourage the Mack Benn students to remember what they’d learned during the Kindness Challenge, two Suffolk police officers and two sheriff’s deputies joined school faculty last week to greet the students and give them a big sendoff for the weekend. There were high-fives and fist-bumps, along with lots of cheering for the children and posters promoting the lessons.

“We’re really trying to model what kindness is about,” school guidance counselor Robin Riddick said.

That’s just the way to promote kindness, and that’s something the world could use a little more of.