A 22-year-old can launch a start-up from their study room, manage millions in funding, and make it to Forbes' 30 list. A 25-year-old can inherit the family business and immediately start calling the shots as CEO. But suggest that a 35-year-old educator with over a decade of classroom experience could lead a school, and suddenly everyone looks shocked. "But do they have the qualities to be a school leader?" they ask. I recently scrolled through job postings for principal positions. "Candidates...