Inside the best public school in America - a charter school that feeds prodigies into the Ivy League

BASIS Scottsdale, a charter school in Arizona, is the best public high school in America.

Its founding dates back nearly 20 years, when two economists struggled to find a school that could provide a rigorous education for their daughter. They started a charter school in Tucson with the belief that the goal of a great education should be to provide students with limitless opportunities. A second high school opened in the affluent suburb of Scottsdale in 2003.

In 2017, four out of the top five public schools - according to a ranking from US News & World Report - are all run by BASIS Educational Group LLC, a for-profit corporation.

Charter schools are public schools that are privately run, either for-profit or not. Their supporters see the schools as providing a leg up for underserved students who lack access to a personalized education, while critics claim that charter schools snatch away limited resources from other public schools.

Polarizing as they may be, charter schools have a track record of success. Business Insider spent the day at BASIS Scottsdale to see what makes it the best in the nation.