the high cost of low teacher quality

Cross posted from Joanne Jacobs:

Education Sector's How Low Teacher Quality Sabotages Advanced High School Math is a must-read. Kevin Carey summarizes:

Students who take advanced math courses in schools that employ the fewest well-qualified teachers are far less likely to be adequately prepared for college, or to succeed in college, than students who take the same courses — or even less advanced courses — at schools with the most well-qualified teachers. Students who fail to take advanced courses do poorly across the board. But it turns out that simply enrolling students in more advanced classes isn't enough — you also need good teachers to teach them.

Illinois makes all 11th graders take the ACT. The llinois Education Research Council combined ACT scores and high school grades to rate each students' college readiness.

To create a Teacher Quality Index (TQI), researchers looked at factors correlated with effectiveness: graduation from a "more competitive" college, less than four years of teaching experience, emergency or provisional teaching credentials, one or more failures on the basic skills test for new teachers, composite ACT score and English ACT score.

Few students who took only algebra and geometry were ready for college regardless of their school's Teacher Quality Index. But TQI correlates with college readiness for students who completed advanced algebra, trigonometry and calculus.

Students who took Calculus in the lowest TQI schools were five times less likely to be well-prepared than students who took Calculus in the highest TQI schools. In fact, students who took Calculus in schools with a TQI below the 10th percentile had a lower preparedness rate (16 percent) than students who only took Algebra II in schools that were above the 25th percentile.

There is a confounding factor: Low-TQI schools tend to be high-poverty schools.

Low-income students, who face some of the greatest barriers to education, are much less likely to be taught by teachers with the best qualifications.

More than 90 percent of well-prepared students and 55 percent of least-prepared students enrolled in college. After three years, 10 percent of the top category and 41 percent of the lowest category had dropped out.

Take a look at the charts: At schools with a TQI in the lowest 11th-25th percentile, less than half of students motivated enough to tackle calculus are prepared to succeed in college. In the bottom 10 percent of TQI, fewer than 20 percent of calculus students are prepared.