Quianna McNaughton, a fourth grade student from Salt Lake's Whittier Elementary, and Marie Terpstra, a senior citizen from the Friendly Neighborhood Center, join forces this week to help decorate the 20-foot Christmas tree in the atrium of the Salt Lake Government Center's north building. While the seniors and fourth graders trimmed the tree with hand-made ornaments, they were serenaded with Christmas carols performed by the center's Kitchenaire Band. The ornaments were made by both groups during joint meetings held on Tuesday afternoons in October and November. The decorating effort was a cooperative program of the Salt Lake City School District's Volunteer Services office and the county's senior citizens centers program.