When a 10-year-old classmate hurt an ankle and began to walk with a limp, Poppy did not see an injury. What Poppy saw was a bullying opportunity.
Walking across the classroom to use the pencil sharpener, Poppy began to affect a limp, too. This became increasingly pronounced as she approached the girl's desk.
Poppy, it is fairly safe to say, is not a kind person.
Angela McCall, Poppy's fifth-grade teacher at Doby's Mill Elementary School in South Carolina, US, would not disagree. "She can be catty or judgemental of her peers," she says. "She can be critical. She's created tension in the classroom."
Nonetheless, McCall maintains that Poppy (a pseudonym - using her real name would challenge anyone's belief in kindness) is not a hopeless case. Kindness, she insists, can be taught to children in school. And she is not alone: an increasing number of school leaders and teachers now see it as their duty to teach children how to be nice to one another.
"Children are kind to themselves," says Geoff Smith, headteacher of Kehelland Village School in Cornwall, in the South West of England. "Every child wants to be first in line to have a treat. They want to give themselves biscuits or computer time.
"They have an embryonic sense of justice. They understand what's fair for them. That inherent selfishness that a little child has - there's nothing wrong with that. But we need to build out from it. They have to understand what's fair for other people as well.
"The old adage is that behaviour is caught, not taught. But if one of my parents said, 'How do you teach mathematics?' and I said, 'We don't teach it. We catch it,' there would obviously be a fair amount of concern. These things need to be taught."
It would be easy to dismiss McCall and Smith's faith in human kindness as the projected goodness of people who have chosen to devote their lives to young children. But psychologists, too, echo this belief.
"Empathy starts developing early," says Marvin Berkowitz, professor of character education at the University of Missouri-St Louis. "You'll see contagious distress. If other people are upset, baby becomes upset, too. That's not empathy, but it's the precursor of empathy.
"And in the second year of life - 18 months or earlier - kids are spontaneously showing acts of kindness. They'll try to soothe someone who's upset - Mommy, or another child. They'll give her their teddy or blanky, to make her feel better."
But if kindness is innate to all children, then they should surely all be naturally disposed to altruism and empathy. Some children, however, simply do not have the skills to display this empathy: no one has taught them to hold a door open for another person, or to say "thank you" when someone does the same for them. And for others, such as Poppy, something has gone more fundamentally wrong.
"Children are likely to replicate their parents," Berkowitz says. "Taken to the extreme, if parents systematically abuse a child and deny them what they need, they're going to break that child."
Children want to make sense of the world, he says. And so they interpret it through the filters of their own experience. This then creates a self-perpetuating cycle, reaffirming what the child believes to be true.
For example, if children have been exposed to antisocial, abusive behaviour at the hands of their parents, they will assume that everyone else they encounter has the same antisocial, abusive intentions. So, if someone brushes up against them in the corridor, they are likely to interpret it as a deliberately hostile act, because experience has taught them that such acts usually are hostile. This then becomes self-fulfilling: the children will respond aggressively to the person who brushed up against them, increasing the likelihood that the other person will be aggressive in return.
"If someone is nice to an abused kid, that kid will push their buttons and try to get the other person to be mean," Berkowitz says. "Because that meanness is the world that makes sense to them."
This, essentially, is the reason for much of Poppy's unkindness in the classroom. "It's the influence of media and television," McCall begins, circumspectly. "And probably in her home, the way things are said to her. I think maybe she doesn't have the best models of kindness.
"But I do believe that kindness is in us all, inherently. Sometimes parents make poor choices. So we have to try and funnel them in the right direction."
The most effective form of funnelling, Berkowitz says, is a process known as "induction". When praising or reprimanding a child, adults should make a point of justifying their behaviour with the language of kindness. So a teacher might say, "The reason I'm so upset with you is that you made Jimmy cry," or, "The reason I'm so proud of you is that you really made Mrs Smith smile - did you see her face?"
"They have to understand the link between what they do and how others feel," Berkowitz says. "Induction is focused specifically on that. It points out and explains how your behaviour affects another."
"When we, as adults, are acknowledged for doing something kind, we glow inside," says Smith, who combines his headship of Kehelland School with work as a "virtue consultant". "Somebody has recognised our basic humanity and that brings us to life, allows us to glow a little bit."
Smith does not use the term "induction". But induction nonetheless underpins much of the interaction between students and staff at his school. For example, when a child holds open a door for a teacher, the teacher will make a point of praising that child's kindness. Similarly, if a student goes out of their way to befriend someone sitting alone in the playground, the teacher on duty will say: "You took time to play with them when they were sitting on their own. Well done for showing kindness."
All of us, Smith says, crave meaningful recognition in life: would it not be good to be rewarded for driving within the speed limit (he suggests a reduction in car insurance) as well as punished for breaking it? "When a teacher acknowledges a child for doing something fair or courageous, it's like they're being acknowledged for the real human being they are," he says.
Of course, when kindness is rewarded with praise and affection, it ceases to be its own reward. Instead, it is nothing more than an altruistic means to a self-serving end: a hoop to be jumped through in order to feel better about yourself.
"There's a huge debate about whether pure altruism exists," says Sonja Lyubomirsky, professor of psychology at the University of California, Riverside. "You can always argue that, when you do something for someone, you do it to make yourself feel better, or for some kind of reward."
But, she says, earning social rewards for kindness makes evolutionary sense. "Human beings need support, help and assistance from one another," she says. "We're social beings.
"When you do nice things for others, they will hopefully return the favour later. It strengthens bonds and relationships. And relationships are critical to survival and to happiness."
This is exactly what McCall has been telling Poppy back in South Carolina. After witnessing the 10-year-old's mocking limp across the classroom, she took her to one side.
"I explained that it really mattered to the other girl that she did that," McCall says. "It really left a bad taste in her mouth. You don't want to do that, because you need friends in this world. You want to have each other's backs."
But if kindness is no longer its own reward, then one may as well be brutally transactional in an effort to encourage it. And so, in some schools, kind deeds are rewarded not only with promises of friendship and social acceptance, but with prizes.
At St Barnabas' Primary School in Lancashire, in the North of England, kindness is among the virtues promoted. In literacy lessons, teachers ask children to write instructions on how to be kind. During religious education, students discuss whether different people's actions demonstrate kindness.
And, to reinforce these messages, children who demonstrate acts of kindness during the week are presented with a yellow ticket. At the end of each week, tickets are placed in a box and two winners are drawn at random.
These two children are then given golden jumpers to wear for a week, and sit in golden chairs ("They're very comfy," says St Barnabas' headteacher, Alison Howarth) during assembly. They are also allowed to choose from a menu of possible rewards. These include having lunch with Howarth, wearing their own clothes to school, playing on the school Wii during lunch hour and sitting in any class of their choosing for a day.
"The children seem to respond to the rewards," Howarth says. "But they also continue to model that kind of behaviour, even when they're not getting the reward. The reward might start them off, if they've not thought about being kind. But, after that, they do it on their own."
Even Poppy, impervious to the ways in which she might be hurting her classmates with her bullying, was not immune to reward. Asked to work on a piece of creative writing during a social studies lesson, she took time and effort over the exercise. She then showed it to two of her classmates, who were so impressed that they told the teacher that Poppy should be allowed to read the essay out loud to the class.
"Her writing was so wonderful," McCall says. "There was a lot of praise from her peers, and I was praising her and hugging her. It was the first time that she showed a genuine, happy smile. The lights came on in her eyes. It was the first time you saw those layers melt away. And it started with those kids showing kindness to her."
There is an appealing fairy-tale simplicity to this story: it demonstrates that there is no evil that cannot be melted away through the judicious application of smiles and kind words. All it lacks, for completion, is an upbeat musical number and the appearance of some cheery woodland creatures.
But real life is not a fairy tale. Real human beings are not good or evil - they are a complex mix of character, circumstance and intention. And adulthood is fraught with ambiguity: can one praise Hitler for being kind to animals? Or admire the creativity of the inventor of the atom bomb, even if the consequences of his invention were far from laudable?
"We had a child who was sharing his lunch with another child every day," Kehelland's Smith says. "We had to explain that he could share it for one day. But it was his own lunch, and was meant just for him. That's not about being unkind."
Similarly, if a child is being bullied, being kind to the bully may prove to be effective in the long term. But in the short term, the victims need to look after their own interests.
"Kindness and justice have to be balanced," Smith says. "You have to have a broad range of virtues. You may need to tell someone that what they're doing is not good enough. Sometimes, to be kind, you have to be flexible."
For example, if someone was stealing your lunch, you would want to value truthfulness above kindness and report the theft to a teacher. But if someone came into school with a dreadful new haircut, tact might be kinder than truthfulness.
"This is a common criticism, that there are very complex decisions in life, which can't be answered just with the application of kindness," Smith says. "But it's like learning to speak and write in complex sentences. You have to understand the basics of speaking and writing to start with, and then combine them and create something more complex.
"It's the same with the virtues. You develop that complexity. But you can only do that when you have the basic building blocks in place."
At Kehelland School, the basics of kindness are encouraged through induction, but also through role play. For example, children might be asked to act out a scenario in which they are watching television when their parents come home from work. They act it out first without kindness - they just keep on watching TV - and the second time with kindness: "Sit down, Dad. Can I make you a cup of tea?" Students then discuss how they feel during the two different scenarios.
Similarly, if children bully their classmates, they are not given a lecture on what they have done wrong. Instead, they are asked to consider how the other child feels. "I need you to practise kindness tomorrow," the teacher might say. "What would you do differently next time? What will you do tomorrow? Thank you for agreeing to that."
But, Smith is quick to point out, his school is no hippy-dippy, consequence-free idyll. Children are also punished for misbehaviour. "Often, teachers tend to go into detective, forensic mode," he says. "What happened? Who did it? Why did they do it? But you very rarely get to the bottom of it. We use positive language to guide, acknowledge and correct. We're always in that educative mode."
Behaviour patterns, however, are carved out notoriously early and notoriously deeply. Even the consistent kindness messages of schools such as Kehelland and St Barnabas are often counterbalanced by years of kindness-free parenting.
"It's easier to change things earlier in the lifespan," Berkowitz concedes. "It's easier at two or three years old to make changes in behaviour. But it's never too late. When someone's 14, that's still relatively early in the lifespan. It'll be a little harder, but it's not too late."
Lyubomirsky has seen this in action. She and several colleagues asked a group of students between the ages of 9 and 11 to perform acts of kindness over a four-week period. She found that these children were not only happier than their classmates at the end of the four weeks, but also more popular.
"There's maybe something hard-wired," Lyubomirsky says. "We're attracted to people who are kind, because they're probably going to be supportive of us and will help us.
"But there's also something conscious there. When people are nice to us, they make us feel better and we want more of it. It's like food: you eat food that tastes better, and then you come back for more."
This is the lesson that McCall hopes Poppy will learn. At the end of the school year, Poppy will go on to middle school, with new teachers and new classmates. And so McCall continues to encourage her to be kind, in the hope that this will ease the transition.
"She's not a real talker," McCall says. "But she does a lot of listening. I try to help her realise that she's not just helping other people by being kind.
"You put good out there and good is going to come back to you. Like my grandmother always said, you can catch more flies with honey than with vinegar.
"I think she's hearing me. But she doesn't say a lot back."