In 1998, when Washington, D.C.’s first charter schools opened, it would have been hard to believe that within two decades the number of students in charters would increase tenfold, or that half of the city’s students would ever be learning at the right pace.

That’s the reality today. Nearly 45 percent of Washington’s public school students are in charters. And more than half of charter school students are proficient in math and reading, according to city tests, and just under half of the students in traditional public schools are.