Emma and her brother,Alex

Throughout her 15-year Schauspielen career, Emma Watson has probably been interviewed thousands of times. But on Wednesday, the Ivy League–educated actress and U.N. Women Goodwill Ambassador had the opportunity to actually ask the questions, and not just to another Hollywood player, but to Malala Yousafzai, the 18-year-old Pakistani activist for female education who, last year, became the youngest-ever Nobel Prize laureate. Although the two have completely different backgrounds, Watson and Yousafzai proved to be the perfect conversational match, as both are young, eloquent activists who have delivered...