In June, 3.3 million American teenagers will graduate from high school. Just 80 percent of them graduate in four years, a share that declines to 65 percent among African-Americans. Yet in the last 40 years, school funding has exploded. The annual per-student cost of primary and secondary education in America now tops $13,000—an increase of 239 percent, adjusted for inflation, over the last half-century. America spends more per student than any other country in the world.

One reason all this spending has not brought better outcomes is that teachers’ unions are more concerned with protecting their members than with helping students. Pay and staffing decisions based on seniority, not skill, don’t serve students’ needs and also leave some American public school teachers disillusioned. Today, many promising young teachers are choosing to apply their talents at charter schools, which don’t offer tenure—but also don’t require their teachers to join unions as a condition of employment. Kimberly Tett opted to teach literature at an inner-city charter school in Chicago rather than at a traditional suburban district school. “I am observed by my instructional coach at least once a week, and each observation is followed by a 45-minute meeting,” she said. “In these meetings, we discuss areas of success, improvement, data analysis, next action steps, etc. Through these meetings and observations, I feel I have grown more as a teacher in just one year than some teachers ever do.”

Charter schools offer many of the same benefits as private schools, since they are free from the stranglehold of teachers’ unions. This leaves them able to experiment with and adopt new education methods, including uniforms and stricter discipline, and to attract successful teachers. While teachers’ unions detest charter schools, the public favors charters by a two-to-one margin. Among African-Americans—arguably the biggest beneficiaries of alternative schooling options—support runs greater than three-to-one. Even 38 percent of public school teachers favor charters, while 35 percent are opposed.

But what about the actual effects of charter schools on student achievement? A stunning 94 percent of high school seniors at Kimberly Tett’s school are accepted into four-year colleges—compared with about 50 percent at traditional Chicago public schools. Math-proficiency gains are three times higher for students at Kimberly’s school than for those in Chicago district schools, and ACT scores are also higher. Since charter school admittance is determined by lotteries, not by academic record, most of these student improvements are likely a direct result of more effective approaches to teaching.

And the success of Kimberly’s charter school is not unusual. Stanford University economics professor Caroline Hoxby found that a student who attended a charter school would close 86 percent of the “Scarsdale–Harlem achievement gap” in math and 66 percent in reading. The gap represents the difference in student achievement, measured by test scores, between one of the wealthiest neighborhoods in the New York metro area and one of the poorest. By the end of eighth grade, students who attended a charter could expect to score 30 points higher on a standardized math test than their peers who missed out on the lottery.

Further evidence can be found in the results at Success Academy Harlem I, a charter school that shares a building with P.S. 149, a traditional New York City public school. The achievement gap between the schools is substantial, though they share a location and student bodies with similar socio-economic composition. At Harlem I, 86 percent of students are proficient in reading and 94 percent are proficient in math. At P.S. 149, only 29 percent of students are proficient in reading and only 34 percent are proficient in math. More than 80 percent of Success Academy students live in families with incomes below the poverty line, but students all across the Success Academy network are excelling. If all 32 schools in the Success Academy network made up a single, large school, it would rank seventh out of the 3,560 New York State schools in math. Overall, 94 percent of Success Academy students are proficient in math and 64 percent are proficient in English-language arts. The averages for New York City are 35 percent and 29 percent, respectively.

This success is one reason why last year, 70,700 students in New York City applied for 21,000 available places in charter schools. Nationwide, over 1 million young people have entered their names on charter school waitlists. If charter school enrollment were 50 percent or higher nationally, Harvard University professor and education-policy expert Paul E. Peterson believes, then U.S. students would be “competitive with the highest-scoring countries in the world.” Certainly, we need more young, enthusiastic teachers such as Kimberly Tett, and more schools that follow Success Academy’s model.