Nearly three years after Taliban gunmen shot Pakistani schoolgirl Malala Yousafzai, the teenage activist challenged world leaders at the United Nations to help millions more children go to school.
Her call last week comes ahead of World Teachers' Day on October 5, a UNESCO initiative highlighting the work of educators struggling to teach children amid intimidation in Pakistan, conflict in Syria or poverty in Vietnam.
Worldwide, the number of schools is growing rapidly - both private schools for the middle class and wealthy and cash-strapped government schools in places like Kenya, where poorly paid teachers have downed tools to demand more pay.
Many schools lack teachers, chairs, electricity or books. Others even lack buildings.
But children seem willing to learn anywhere. Classes are in corridors in the Philippines, onboard boats in Brazil or in a local park in Pakistan.