Are charter schools public schools? At least one presidential candidate seems unsure: Sen. Bernie Sanders recently told an Ohio audience, “I believe in public education, and I believe in public charter schools. I do not believe in private – privately controlled charter schools.”

Those comments provoked umbrage from charter school advocates, glee from charter critics, perplexity from journalists, and indifference from people who don’t closely follow education debates. But Sanders’ remarks also inadvertently reveal a much broader issue: Americans are confused about what it means to be a public school.