The former head of Britain’s most famous private school thinks kids need to fail and learn from the experience.

Tony Little was the headmaster of Eton, which 19 British prime ministers—including the current one—have attended, for 13 years. During his time there, Little grew increasingly concerned about “boys and girls who had gilded school experiences.” He feared for the school children “for whom it had been very straightforward, always good at exams, always popular, always found the flow easy to deal with,” warning that they may not have developed the “resilience” for struggles in adult life.

“I think it behoves all great schools to make sure all their children fail,” he said. ”Not just have the experience of failure, but of course within a supportive context, to learn from that experience of failure.”

Little made the remarks at Global Education and Skills Forum in Dubai, where a Palestinian ex-refugee won a prestigious prize dubbed the “Nobel for teachers.”

Quartz has reportedly previously that the ability to recover from early adversity is critical for success. It may be one of the best way to learn math, and there’s even some research to suggest that those who worry about failure could be better off than those who cope with stress differently.

And it’s not just schools that need to let kids fail to help them build this resilience. Parents should also let their kids fail so they grow up more autonomous and competent.