On Martin Luther King Day, the halls of the Jewish Federation of Northern Jersey were alive with the sound of kids working and laughing together.

The first Day of Service for Students brought 85 kids — mostly in middle school — from diverse communities in Bergen County to work together for the community and get to know each other. Some wore kipot, others a Muslim hijab or a Sikh turban. Most were bareheaded.

They bagged supplies for the homeless, drew signs for a community garden, wrote postcards to soldiers, and painted a “tree of us” that now hangs at the federation’s office in Paramus.

They also got to know each other in structured conversations, where they learned about each others’ favorite foods and religious practices.

“I had a lot of fun,” said Zareena Al-Shehab, 13, a Muslim eighth-grader at the Thomas Jefferson Middle School in Teaneck. “I learned a lot about the Sikh community and the Jewish community.

“I’ve done service with people of other religions, like packathon for Haiti,” she said. “This was the first time we were actually discussing our religion and engaging in conversation with other people about religion. It worked out great.”

Martin Luther King Jr. used to speak of the “fierce urgency of now.” The day of service grew from the fierce urgency that Tracy Zur felt the morning after the election. Ms. Zur lives in Ridgewood. She is a Bergen Country freeholder, a mother of three, and an active member of the Jewish community, having served on boards of the Jewish federation and the Academies at Gerrard Berman Day School in Oakland.

“There was so much division,” she said. “We needed to come together as a community.”

Ms. Zur started talking with her friends about what to do. Something to highlight Bergen County’s diversity. Something involving children, who, she noted, had been paying attention during the ugly election campaign.

And then there was the Martin Luther King holiday, which often seems like it’s just a day off from school but calls for a deeper observance.

“Tracy reached out to me and said she wanted to do something meaningful with the kids,” Yasmeen Al-Shehab, Zareena’s mother, said. “My kids in particular were very anxious with all the talk of a Muslim registry and a Muslim ban. I was on board immediately.”

The organizers drew students from Teaneck’s Muslim community; the Sikh community centered around the Glen Rock temple; the local chapter of Jack and Jill of America, an African American family organization; the Academy of Saint Paul, a Catholic school in Ramsey, and two Jewish day schools, the Gerrard Berman and Yeshivat He’Atid in Teaneck.

It was natural for the federation to open its doors for the day of service, according to Barbara Selman, co-chair of the federation’s intergroup relations committee.

“This is what we as Jews do,” she said. Through Federation we are reaching out to others, learning about each other and forming friendships. It’s important that other groups in our community get to know us, to know that we care about them, and for them to care about us.”