Vanessa Hermione Greening, aged 49, and a drama teacher in Tipton was found guilty of common assault by magistrates and now faces the sack after a career in the classroom spanning 30 years.
Greening was sentenced to a six-month community order. She ended up in court after the parents of the pupil at Alexandra High School, Tipton, complained to teachers who then contacted the police.
Sandwell Magistrates Court court heard she lost her temper as children watched another group perform last February.
The 13-year-old victim who was next to Greening, had admitted to speaking when he shouldn't but said on this occasion he had not.
Mrs Kelly Crowe, prosecuting, said: "Whilst they were watching the group do the piece of work, someone spoke, and the defendant who had a folder in her hand slammed it once to his head."The court heard the boy was shocked but was uninjured and later told police later "it didn't hurt".
It was told Greening, of Dunsford Road, Bearwood, had been previously reprimanded for her conduct.
Miss Laura Culley, defending, said the teacher did not accept that the incident happened intentionally or otherwise. She had pleased not guilty.
Headteacher Ian Binnie said the school's disciplinary procedures were under way.