A 15-year-old schoolgirl was left "humiliated" and in tears after teachers showed her classmates a picture of her in a bikini as part of an assembly about social media safety.
Staff at the Eggbuckland Community colleague in Plymouth found pictures of their students online and showed them to the group of 100 teenagers to illustrate the dangers of sharing sensitive images.
But the schoolgirl told her mother the exercise left her humiliated and embarrassed.
The girl's mum has now lodged an official complaint with the education watchdog Ofsted.
"They took the photo from her Facebook profile - she put it on there last year," she said.
"They used other photos of kids from the neck up but for some reason they thought it was OK to use a picture of my daughter in her bikini.
"Why did they have to use an image like that to make their point. Then they pointed her out in the assembly. She was really upset.
"I got a phone call from my daughter in the afternoon. When she told me about it I went from nought to sixty. I was so upset at work I was sent home.
"She's really upset and hurt and this has knocked her confidence. She's not the type of girl who likes attention like this.
"She's a tom-boy, she doesn't wear make-up and she doesn't even have her ears pierced. It's not often you even get her in a bikini."
A Plymouth City Council spokesperson said on behalf of the school, whose motto is "Learning, caring, achieving":