Even with the best technology in the world, there is one key element that determines student success: a high-quality, highly-effective teacher.

In fact, some research estimates that teachers can impact students’ lifetime earnings by 10 to 20 percent, which can increase the U.S. gross domestic product by tens of trillions of dollars.

And professional development (PD) is critical in helping teachers as they continue to hone their skills and evolve as educators. But what kind of PD is most effective, and does the kind of PD that helps teachers best change as teachers become more experienced?

A new study series tackles those very questions.

The report, Investing in What it Takes to Move From Good to Great, is the third in a series that (the third in the study series) summarizes findings from a 2016 survey of National Board Certified Teachers (NBCTs) and builds on the results of a similar survey of State and National Teachers of the Year in 2013–2014.

(Next page: PD approaches, along with policy recommendations, for teachers at every stage of their careers)