You hold your tray. You survey the room. You pray for a friendly face.

There’s a reason why the sterile school cafeteria is a metaphor for a potentially cold reality of growing up, not to mention the scene of many coming-of-age films.

Nothing quite like sitting alone with a brown bag and a bologna sandwich to make us want to disappear.

There’s a reason, too, why the lunchroom stars in a heartening effort to encourage kids who are not yet friends to look up and consider the possibility.

For years, I’ve wondered whether Mix It Up at Lunch Day, a simple social experiment running in nearly 8,000 schools nationwide throughout October, could possibly make a difference to our increasingly diverse and technologically wired children. The national campaign encourages schools to use the lunch break to help students push past social boundaries.

Cool. But 20 minutes to eat — and change the world?

After observing, I’d say the effort certainly takes a bite out of the challenge. And it’s food for thought for grown-ups, too.

“It’s very hard to sit with someone you don’t know,” said Antonio, a sixth-grader at Jefferson Community School in Minneapolis.

Antonio, a thoughtful kid who rarely sits alone, was in the school lunchroom on a recent Friday, helping to hang signs with icebreaker questions. “If you could go on vacation, where would you go?” “What do you like about school?” “What is your favorite color? Movie? Book?”

His lunchroom was anything but sterile. Balloons decorated a baker’s dozen of tables, each covered in brightly colored tablecloths: blue, orange, green, yellow, red. Coached by enthusiastic school staffers and Principal Bridget Hall, the students filed in, matching their name tag’s color to the color of the table they would be assigned to.

Scary? Even I felt jittery.

Fifth-grader Treyvon stalled at the end of his table, not sure what to make of the situation. Third-grader Christelle shook her head “no” when asked if she wanted to meet the boy sitting across from her.

OK, the project’s not perfect. But there were plenty of promising moments. “I didn’t know her, but I did talk to her!” said fifth-grader Emily. “I said, ‘What grade are you in?’ ”

Nataly and Vanessa told me that they’re in the same class, but have never talked until today. Now they can’t stop.

736 kids, 14 languages

This warming trend over pizza didn’t surprise Curt Carpenter, an elementary school principal in Minnetonka who served on the governor’s Anti-Bullying Task Force.

“Kids are social creatures,” Carpenter said. “They really do believe they’re going to meet new friends.” He didn’t even need 20 minutes to learn that himself.

He was once a kid heading to lunch wearing a “corny” key collection around his neck. His teacher asked him to “please show new student Glen around.” The pair have been close friends ever since.

“Kids don’t have the biases and prejudices we have as adults,” Carpenter said. “That’s learned over time.”

Or not learned over time, if we can be our best selves as their parents and mentors. Jefferson is a great test school for such a program. Its 736 children in pre-kindergarten through eighth grade speak 14 languages.

Colleges also participate

“Students have told us over the years that the cafeteria is where they see the most divisions,” said Monita Bell, a spokeswoman for Teaching Tolerance, a program of the Southern Poverty Law Center, which launched Mix It Up ( 14 years ago.

“The cafeteria, traditionally, is when students break off into their groups; often racially segregated or by other kinds of segregation. That’s not necessarily a bad thing. There is an affinity, and you take comfort in people who share your identities.

“But it can be a place that is very exclusionary,” said Bell, noting that choosing October, which is National Bullying Prevention Month, was strategic. “For kids who don’t fit easily into a group, imagine what that must feel like.”

Schools are trying all sorts of creative ideas to show kids that they are more alike than different. Some are setting up lunch tables by birth month or by the first letter of a last name. One school divided students by the results of a personality test.

“This event isn’t going to change the world,” Bell said. “But if it helps one second-grader understand that ‘I don’t have to be afraid around someone I don’t know,’ that can be an eye-opener that can change the way that child sees the world.”

That’s true far beyond second grade. Bell was surprised to learn more than 70 colleges and universities are registered to participate in Mix It Up.

“Love it,” she said. “And it makes sense. We’re going out into a world that is increasingly global.” Practicing ways to keep an open mind, and an open seat at the table, moves us closer to each other.

“Life is about mixing it up,” Bell said. “If you’re not able to do that, you’re going to enter the world with a huge deficit.”

Positive feedback

Heather Von Bank was happy to hear about the growing popularity of Mix It Up, with one caveat.

“I like the effort, and I like thinking about mixing it up,” said Von Bank, an assistant professor of family studies at Minnesota State University, Mankato, who specializes in family life and adolescents.

“But teens often have their peer groups set by age 3 or 4. I would imagine it would be better if they mixed it up and stuck with that mixed group for a longer period of time, as a really nice step to knowing people on a personal level.”

Back at Jefferson, Von Bank’s sentiment was gaining steam. Feedback about the unusual lunch day was overwhelmingly positive, said school administrator Ashley Gillingham. Two second-grade girls gleefully told their teacher that they had made new friends. Others learned that “we may look different, but we like to play the same games at recess,” she said.

The staff was so happy with the outcome that they plan to hold the sweet meet-and-greet on a weekly basis.

Said Gillingham: “We’ll call it Mix It Up Mondays.”