A national study released last week shows charter school students doing slightly better than their public school peers in reading and about the same in math. Results varied greatly from state to state and among various subgroups of students.

Poor, black and Hispanic English-language learners, for example, made bigger gains than whites. And the District of Columbia and Rhode Island did better than Oregon and Nevada.

The study, from the Center for Research on Education Outcomes at Stanford University, seeks to answer the critical question about whether charter school students are getting a good education. The answer from this study is clearly yes — on average — although poorer performing schools can no doubt learn from their more successful peers, and sponsoring districts need to provide oversight.

But it’s critical to remember a chief reason charter schools exist: They give students and parents choices.

Charter schools in Oregon have been around for more than a decade. They are operated by parents, teachers and community members, using public money. They have a contract with a sponsoring entity, often the local school district, and operate semi-autonomously.

Oregon’s Department of Education handbook on charter schools lists nine purposes for charter schools, and right after “Increase student learning and achievement” is “Increase choices of learning opportunities for students.” Next comes “Better meet individual student academic needs and interest,” and later on is “Encourage the use of different and innovative learning methods.”

The idea is that charters, which can hire non-union teachers and operate with less bureaucracy, are free to innovate on a wide range of issues, finding methods that serve some students more successfully.

Opponents have complained that charters drain resources from traditional public schools. Randi Weingarten, president of the American Federation of Teachers, said the study results should prompt us to “pause and ask ourselves why we keep pitting charter schools against neighborhood public schools,” according to a report in The Wall Street Journal.

We think that’s the wrong way to look at it. Choice and innovation serve not just individual students, but the whole system, by encouraging experimentation and discovery.