Great article on Greater Good, to foster kindness in kids ...
 

A recent study by Arber Tasimi, a graduate student at Yale University, and Liane Young, a professor at Boston College, found that kids who do good—and think back on it—are driven to do more and more good. As Tasimi says, “These findings show that something as simple as asking children to reflect on their past good deeds has positive effects on children’s behavior.”

If we want to raise kind children, this study suggests, we can reinforce good behavior by telling stories about their past kindnesses and offering gentle reminders when they’re deciding whether to share. (And a key way to motivate good behavior in the first place, according to a 2014 study, is for parents, educators, and other trusted adults in kids’ lives to invite them to be helpers, rather than informing them they can help—so helping becomes part of their identity.)