'Education is my way out' of Nigeria's floating slum
John Mary is paid $1 (75p) a day to teach children in the world's largest floating slum, but she's determined to leave and go to university.
In Makoko, Lagos, many girls are pregnant by the age of 13, but John Mary has always wanted a different life.
She told BBC Minute: "Makoko is a very dirty place, but education is my way out."
Video Journalist: Dan Ikpoyi