The following post was written by Jill Barshay and reposted by Larry Cuban on his blog. It is a response to the claim by various economists that teachers don’t improve after three to five years. This claim has been used to promote Teach for America, despite their inexperience and lack of substantive teacher education. It has also been used, as the previous post about North Carolina shows, to claim that teachers should not be paid based on their experience. It’s a pernicious idea, and I thank Larry Cuban for featuring this debunking of the conventional but wrong “wisdom.”

Jill Barshay writes:

The idea that teachers stop getting better after their first few years on the job has become widely accepted by both policymakers and the public. Philanthropist and former Microsoft CEO Bill Gates popularized the notion in a 2009 TED Talk when he said “once somebody has taught for three years, their teaching quality does not change thereafter.” He argued that teacher effectiveness should be measured and good teachers rewarded.

That teachers stop improving after three years was, perhaps, an overly simplistic exaggeration but it was based on sound research at the time. In a 2004 paper, economist Jonah Rockoff, now at Columbia Business School, tracked how teachers improved over their careers and noticed that teachers were getting better at their jobs by leaps and bounds at first, as measured by their ability to raise their students’ achievement test scores. But then, their effectiveness or productivity plateaued after three to 10 years on the job. For example, student achievement in their classrooms might increase by the same 50 points every year. The annual jump in their students’ test scores didn’t grow larger. Other researchers, including Stanford University’s Eric Hanushek, found the same.

But now, a new nonprofit organization that seeks to improve teaching, the Research Partnership for Professional Learning, says the conventional wisdom that veteran teachers stop getting better is one of several myths about teaching. The organization says that several groups of researchers have since found that teachers continue to improve, albeit at a slower rate, well into their mid careers.

“It’s not true that teachers stop improving,” said John Papay, an associate professor of education and economics at Brown University. “The science has evolved.”

Papay cited his own 2015 study with Matt Kraft, along with a 2017 study of middle school teachers in North Carolina and a 2011 study of elementary and middle school teachers. These analyses all found that teachers continue to improve beyond their first five years. Papay and Kraft calculated that teachers increased student performance by about half as much between their 5th and 15th year on the job as they did during the first five years of their career. The data are unclear after year 15.

Using test scores to measure teacher quality can be controversial. Papay also looked atother measures of how well teachers teach, such as ratings of their ability to ask probing questions, generate vibrant classroom discussions and handle students’ mistakes and confusion. Again, Papay found that more seasoned teachers were continuing to improve at their profession beyond the first five years of their career. Old dogs do appear to learn new tricks.

The debate over whether teachers get better with experience has had big implications. It has prompted the public to question union pay schedules. Why pay teachers more who’ve been on the job longer if they’re no better than a third-year teacher? It has encouraged school systems to fire “bad” teachers because ineffective teachers were thought to be unlikely to improve. It has also been a way of justifying high turnover in the field. If there’s no added value to veteran teachers, why bother to hang on to them, or invest more in them? Maybe it’s okay if thousands of teachers leave the profession every year if we can replace them with loads of new ones who learn the job fast.

So, how is it that highly regarded quantitative researchers could be coming to such different conclusions when they add up the numbers?

It turns out that it’s really complicated to calculate how much teachers improve every year. It’s simple enough to look up their students’ test scores and see how much they’ve gone up. But it’s unclear how much of the test score gain we can attribute to a teacher. Imagine a teacher who had a classroom of struggling students one year followed by a classroom of high achievers the next year. The bright, motivated students might learn more no matter who their teacher was; it would be misleading to say this teacher had improved.