Frightening footage has emerged of a group of American high school students subjecting a despondent teacher to a barrage of abuse and intimidation inside the classroom. In the short clip, an out-of-control student (pictured clockwise from top left) can been seen throwing things at her, telling her to 'sit your a** down' and threatening her with a chair. While he continues to provoke the teacher (inset), others in the room laugh and encourage him. The incident was reportedly filmed at Chicago Vocational Career Academy.