Two types of public schools showed greater improvement than NYC schools as a whole on 2017’s third- through eighth-grade standardized tests in math and English: charter schools, which were outperforming the average, and schools in the city’s Renewal program, created in 2014 to reform troubled schools, which were badly underperforming the average.

City schools as a whole saw an English proficiency increase of 2.6 percentage points to 40.6 percent. Renewal schools had a jump of 3.2 percentage points, to 15.9 percent. And charter English scores leapt 5.2 points, to 48.2 percent. In math, citywide proficiency increased 1.4 points to 37.8, while Renewal school scores rose 1.5 points to 9.4 percent, and charter school math proficiency was up 3 points, to 51.7 percent. While Renewal school numbers are still low, such schools can also be the toughest to improve, so the progress deserves its due.

Neither Renewal schools nor charters can be judged as blocs. There are successful and unsuccessful examples of both. Success Academy, the city’s biggest charter school network, reported passing scores for a staggering 95 percent of its students in math and 84 percent in English. And the city’s Education Department said some of the Renewal schools are doing so well they could soon be taken out of the program. But some charters are poorly run and fail their students. And some Renewal schools are so bad that officials say they may have to close.

But even with mixed results, the fact that both alternatives are improving student proficiency faster than mainstream schools provides important lessons about what has to happen in NYC public schools as a whole.

Renewal schools receive added resources that include more teacher training, wraparound services to help both students and their families beyond academics, and a longer school day. Many charter schools also have a longer school day (and school year) than mainstream city schools, and they focus on discipline, rigor and critical thinking.

These are things all schools need. And the city needs an education system that, rather than being defined by tradition, work rules and politics, replicates the most successful methods to deliver the best possible educations.