One man is trying to educate the entire world for free.
It all started in 2004, when financial analyst Salman Khan posted some math tutorials for his cousin on YouTube.
About ten years later, his teachings have become known as Khan Academy, a website with more than 4,000 lessons on subjects ranging from basic math to economics – even art history.
Six million people visit the site each month and now Khan wants to reinvent the way children learn in classrooms around the world.
In the video above, CNN's Christiane Amanpour takes one of Khan's tutorials.