A true friendship is a bond built on trust, and when that trust is broken, the friendship often shatters. Bren Brown has spent decades researching trust and vulnerability, and easily tells other adults about the incredible power of leaning into vulnerability, especially in their relationships with others. Children, however, are a different story.

When Brown's own young daughter had her trust unexpectedly betrayed by friends, the mother and researcher had to set aside her protective-parent armor and figure out a way to discuss trust in a way that would make sense to a young mind. What she came up with was nothing short of brilliant.

It all began when Brown's third-grade daughter, Ellen, came home from school and immediately broke down into tears. Brown recounts the memorable moment during a talk for OWN's "SuperSoul Sessions" speaker series .

"She literally just started sobbing and slid down the door, until she was just kind of a heap of crying on the floor," Brown says of her daughter.

As a mom, Brown was frightened and asked Ellen repeatedly what had happened.

"She pulled herself together enough to say, 'Something really hard happened to me today at school and I shared it with a couple of my friends during recess. And by the time we got back into the classroom, everyone in my class knew what had happened. They were laughing at me and pointing and calling me names,'" she says.

The incident had been so disruptive that Ellen's teacher issued a consequence to the whole class: She removed marbles out of the classroom "marble jar," a marker for the students' behavior. When the children make good choices together, marbles are added. When they make poor choices and are disruptive, marbles get removed. When the marble jar gets filled, the class gets a celebration.

Though the consequence was issued, Ellen was no less devastated by the time she got home.

"She said, 'It was one of the worst moments of my life,'" Brown says. "She looked at me, just with this face that is just seared into my mind and said, 'I will never trust anyone again.'"

Brown's immediate reaction was to launch into mama-bear mode, but she settled down so she could clearly explain the concept of trust to her teary daughter in a way that Ellen would understand.

"I took a deep breath and I said, 'Ellen, trust is like a marble jar You share those hard stories and those hard things that are happening to you with friends who, overtime, you've filled up their marble jar,'" Brown says.

In other words, like receiving a celebration from Ellen's classroom marble jar, trust is a reward that must be earned.

This explanation was exactly what Ellen needed to hear. "[I asked], 'Does that make sense?'" Brown says. "That's what Ellen said: 'Yes, that makes sense!'"

Watch Brene Brown's full 24-min. session about the anatomy of trust

More mini-sessions from SuperSoul.tv

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