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This Article is taken from, and can be read in full at, BBC NEWSBEAT
Ten-year-old Kayleigh has moderate Special Needs and is normally very shy, says her Headteacher, Colin Millar. "She'd be a very quiet little girl, but when she sings, she just opens up," he tells Newsbeat.
Kayleigh is one of 200 students, aged three to sixteen, at Killard House School, in Newtownards, Northern Ireland. She started at the school in year four and has learning delays with literacy and numeracy.
This school's Carol concert, at First Newtownards Presbyterian Church, left many of the congregation in tears.
The video, filmed by Billy McAuley, was then uploaded to Facebook and YouTube, and reported in the local Press. It has been viewed more than 100,000 times on Facebook and shared thousands of times. The school has also had calls from people in Australia, America and Japan who have all seen the video.
WATCH THE VIDEO FOR YOURSELF AT BBC NEWSBEAT