The ninth annual tree lighting on the Lynnfield Common is scheduled for Saturday. Santa will arrive at 3 p.m., followed by a community sing-along led by the Girl Scouts of Lynnfield and Tri-M Music Honor Society from Lynnfield High School at 4:15 p.m., and the tree lighting at 4:30 p.m. Other festivities scheduled on or near the common include a country store run by the Historical Society at the Meeting House, and a Gingerbread House Contest open to the public from 10 a.m. to 5 p.m. at the Centre Congregational Church.