First lady Michelle Obama, center left, pours a smoothie mix on a cup while sitting with students at Philip's Academy Charter School as part of her American Garden Tour visit, Thursday, April 7, 2016, in Newark, N.J. (AP Photo/Julio Cortez)
First lady Michelle Obama, center left, pours a smoothie mix on a cup while sitting with students at Philip's Academy Charter School as part of her American Garden Tour visit, Thursday, April 7, 2016, in Newark, N.J. (AP Photo/Julio Cortez)

Last week, U.S. President-elect Donald Trump nominated Betsy DeVos to be the secretary of education in his administration.

DeVos is an education activist who supports school choice, a term for policies that let students and their families choose between attending private or public schools.

Devos has been a leading supporter of charter schools.

What are charter schools?

The American state of Minnesota passed the country’s first charter school law in the early 1990s. Since then, charter schools have spread from coast to coast.

There are currently more than 6,700 charter schools, educating nearly 3 million students nationwide. Those numbers come from the National Alliance for Public Charter Schools, a nonprofit organization.

Charter schools are a kind of public school that receives a special charter, or written rules, from a state government.

A charter is a document, or series of documents, that gives rights to a person or group of individuals.

Charter schools cannot require students to pay tuition for their education; instead, the schools receive public funding. The schools also cannot set admissions requirements. If too many young people asked to be admitted, the school must choose its students through a lottery system.

Charter schools differ from public schools in many ways. They often have flexibility in the kinds of classes and programs that they can offer. They often do not have to follow the rules public schools do.

Jon Valant, an education expert at the Brookings Institution, a public policy group, says the charter school movement grew out of unhappiness with public schools.

Over time, different groups began supporting the charter cause. Civil rights groups wanted schools that broke down barriers based on race or wealth. Parents wanted greater ability to choose where their children went to school. Some Americans said that competition between schools could improve the quality of education.

The main idea was that increased flexibility in an education program would let charter schools better serve their students.

Why do Americans debate charter schools?

Not all Americans like charter schools.

For over 20 years, critics have argued that charter schools take money away from public schools, and may not serve students with special needs.

Some civil rights groups have opposed charter schools.

The NAACP and Black Lives Matter movement, for example, have released statements criticizing charter schools. They say that charter schools have exacerbated segregation, increasing racial barriers. The groups have also criticized the use of suspension as a punishment in charter schools. They point to studies that suggest that charter schools are more likely to suspend minority students.

Some labor and union organizers disagree about whether charter schools are actually public schools. The National Labor Relations Board, for example, recently ruled in two cases teachers at charter schools operate under rules that govern private sector employees.* Traditionally, public school teachers are subject to laws for public employees.

What does the evidence about charter schools say?

In the United States, tests are often used to measure educational success.

When opponents and supporters of charter schools talk about a school’s performance, they are often talking about state test results. Whether current state tests are the best way to measure success is a subject of debate.

Valant, at Brookings, explains what the evidence shows about state tests and charter schools:

"The best evidence we have now is that if you look across the country, kids in charter schools perform similarly on state tests to kids who are in similar schools. So it doesn't look like there are very large effects across the board on test scores."

Valant goes on to explain that charter schools are not all the same. Some charter schools do a better job than others do:

"Having said that, the effects on test scores are more positive in urban areas, which is where there is a lot of energy behind charter schools, so that's where you do tend to see charters outperforming some of the local traditional public schools on state tests."

Another point, Valant adds, is that one of the hopes of charter school founders was to desegregate American schools. In reality, it has not been able to make that change.

Founders also hoped charter schools would increase competition with public schools, leading all schools to improve. To date, there is no proof that the competition has improved public school quality. "That evidence just isn't there," Valant says.

What does the debate over charter schools show you about America?

Michael Hansen, an education expert at the Brookings Institution, thinks the debates over charter schools show that some Americans are suspicious of the idea of public money going to private interests. A common misconception is that charter schools have ties to private organizations, such as religious groups.

Valant adds that the charter movement has appealed to Americans with different beliefs. This appeal, which has not been true of other education reform ideas, helps to explain some of the growth of charter schools.

Charter schools have not unified both political parties, Valant explains, but these schools have found enough support in the country’s two leading parties.

"I think that support," he adds, "has been important in the sustained development of what is a pretty fundamental restructuring of the way that schools are governed."