GORHAM – Wearing a black “staff” shirt, Duncan Gelder stepped to the microphone Friday to lead students attending a community-service conference.

The 13-year-old was one of a group of Auburn middle-schoolers running the 2007 Kids Consortium Student Summit.

“I’m Duncan, and I’m going to explain team-building to you,” he said to a room full of students.

He told them they had to make a musical instrument from material they were given, write a short song and sing it while playing the instrument.

Seventeen Auburn Middle School students have worked since October to organize and plan the seventh annual service-learning summit attended by students from all over New England. Auburn students were in charge of everything from designing the logo on their shirts and brochures to lining up speakers and raising money.

This year was the largest conference so far, with 320 students participating, said Barbara Kaufman of Kids Consortium of Lewiston. The group works with schools on service-learning projects, such as helping in soup kitchens, conducting food drives, planting community gardens, preventing bullying and helping with animal rescue.

The consortium hosts the annual conference to allow students to “learn about different social issues and what each other is doing in their own communities to make life better,” Kaufman said.

Each year students from a different school help to create and run the conference. “This gives them a more global sense of the power of what students can do,” Kaufman said.

One of Duncan Gelder’s jobs was to line up communications equipment. He tried to get cell phone companies to donate phones, but that didn’t work. Plan B was to get walkie-talkies donated. That fell through too, he said, so he moved to Plan C. He asked student planners to bring their own cell phones or borrow from their parents. That worked out, Gelder said.

The whole experience brought student planners closer, he said. “At first we couldn’t agree on who was going to facilitate the next meeting. It’s amazing how well we get along now.”