According to the findings of a National Bureau of Economic Research report, teaching quality is closely reflected by test scores—when looking at a teacher’s impact on students’s test score gains from year to year. This concept called “value-added” (VA) is a helpful way to measure teacher quality by identifying the knowledge a child gained each year. Moreover, it illustrates the importance of skilled teachers.
The study uses school district test scores and United States tax data to follow a group of students from elementary school to early adulthood. It looked at 18 million math and reading tests for 2.5 million children from 1989-2009. It was able to link nearly 90% of school data to tax records on parent and students’ future financial performance.
According to the report (emphasis added):
Students assigned to high-VA teachers are more likely to attend college, attend higher-ranked colleges, earn higher salaries, live in higher SES neighborhoods, and save more for retirement. They are also less likely to have children as teenagers. Teachers have large impacts in all grades from 4 to 8. On average, a one standard deviation improvement in teacher VA in a single grade raises earnings by about 1% at age 28. Replacing a teacher whose VA is in the bottom 5% with an average teacher would increase students’ lifetime income by more than $250,000 for the average classroom in our sample. We conclude that good teachers create substantial economic value and that test score impacts are helpful in identifying such teachers.
Gov. Tom Corbett supports tying teachers’ salaries to student progress, instead of tenure. One objection to relating teachers’ salaries to student progress is that it will incentivize teaching to the test or cheating. But given how valuable good teachers are, it is appropriate to examine ways to reward and retain good teachers, restoring the focus of public education to student learning.