the rafters were rattling with the sound of bluegrass music at Hillsboro Elementary School last Friday. At right: after members of the Black Mountain Bluegrass Boys performed, they gave the students a chance to strum a tune. Richard Hefner lets Jackson Tankersley try the banjo.dancer Becky Hill teaches first grade and preschool students how to clog and flatfoot. From left: Alida McNeel, James Goldsberry and Kaydance White listen intently as they try out the steps. S. Stewart photos