Girls as young as eight are being sent to sex camps in Mozambique and Zambia that are designed to prepare them for marriage by teaching them how to be good at sex.
The sordid training begins as soon as the girl begins menstruating and sometimes involves sticks being inserted inside the girls, according to child protection activists.
If girls are deemed to have performed the sexual acts incorrectly they are cut by the women in charge as punishment, according to Persilia Muianga of international aid agency World Vision.
The practice was revealed at an international conference on ending child marriage, held in the Morrocan city of Casablanca this week.
Muianga - a child protection expert - went on to explain that some mothers in the communities force their daughters to sleep with a man before they have even begun menstruating, in the belief that this can bring on menstruation earlier.
Mystery surrounds the schooling for those who have not been initiated at the camps, creating an attraction in the communities for the week-long training.