South Africa's deadly riots that started in a classroom
18 June 2014 Last updated at 00:58 BST
In 1976, the apartheid government in South Africa introduced Afrikaans as the first language of Soweto schools.
In response, students living in Soweto took to the streets to protest at the changes.
The government met the protestors with brutal force, with the ensuing violence shocking the world.
Bongi Mkhabela was one of the school girls who led the protests.
Almost 40 years on, Bongi spoke to the BBC about what moved her friends to speak out and her memories of the vicious response that followed.
Witness is a World Service radio programme of the stories of our times told by the people who were there.
Produced by Alex Last and Directed by Claire Tailyour