By Dr. Marciene Mattleman

PHILADELPHIA (CBS) - It turns out that telling kids to be nice really works.

In a study believed to be the first intervention of preteen prosocial behaviors, findings showed that doing good for others versus doing a simple pleasant activity could increase happiness and improve peer relations.

In research led by Kristin Layous of the University of California, Riverside, 415 students, 9-11, were instructed to perform 3 acts of kindness or visit 3 places each week for 4 weeks. Kind acts included “giving mom a hug when she was stressed” and “giving someone part of my lunch.”

Visits included shopping centers and baseball fields.

Results revealed that doing something good benefits the givers, earning popularity. And the motto “Be nice” accepted by all students at KIPP schools, the most successful charter network in the nation, changes social climate, where being nice as a character trait is as important as building skills.

Read more about Kindness Counts: Promoting Prosocial Behavior.