Maria Montessori stands in many ways as the mother of alternative education. The Italian physician and teacher invented a new kind of school, one with self-directed learning, classrooms with mixed age groups, and no grades. Now, on what would have been her 142 birthday, thousands of schools bear her name. These Montessori schools have some very famous alumni, many of which credit the free-flowing classes with teaching them to think differently and allowing them to change the world. Here are 10 of the most prominent.