In her first speech since the Taliban in Pakistan tried to kill her, Malala Yousafzai celebrated her 16th birthday at the United Nations, appealing for compulsory free schooling for all children.
Wearing a pink head scarf, Ms Yousafzai told UN Secretary-General Ban Ki-moon and nearly 1,000 students from around the world that education was the only way to improve lives.
"Let us pick up our books and pens. They are our most powerful weapons. One child, one teacher, one pen and one book can change the world. Education is the only solution," she said.
Ms Yousafzai was shot in the head at close range by gunmen in October as she left school in Pakistan's Swat Valley.
She was attacked after campaigning against the Islamist Taliban efforts to deny women education.
She presented Mr Ban with a petition signed by nearly 4 million people in support of 57 million children who are not able to go to school and demanding that world leaders fund new teachers, schools and books and end child labour, marriage and trafficking.
UN Special Envoy for Global Education, former British Prime Minister Gordon Brown, said the event was not just a celebration of Malala's birthday and her recovery, but of her vision.
"Her dream that nothing, no political indifference, no government inaction, no intimidation, no threats, no assassin's bullets should ever deny the right of every single child ... to be able to go to school," said Mr Brown.
Pakistan has 5 million children out of school, a number only surpassed by Nigeria, which has more than 10 million children out of school, according to UN cultural agency UNESCO. Most of those are girls.
Islamist gunmen killed 27 students and a teacher on Saturday in a boarding school in northeast Nigeria.
It was the deadliest of at least three attacks on schools in Nigeria since the military launched an offensive in May to try to crush Islamist insurgent group Boko Haram, whose nickname translates as "Western education is sinful" in the northern Hausa language.
The Taliban claimed responsibility for the assassination attempt on Ms Yousafzai, calling her efforts pro-Western. Two of her classmates were also wounded.
Ms Yousafzai was treated in Britain, where doctors mended parts of her skull with a titanium plate. Unable to safely return to Pakistan, she started at a school in Birmingham in March.