New research finds that teachers who work in supportive professional environments show greater gains in effectiveness than teachers in schools that are less supportive.

For a study published in Educational Evaluation and Policy Analysis, researchers Mathew A. Kraft and John P. Papay of Brown University studied teachers working in North Carolina’s Charlotte-Mecklenburg school district, the 18th largest district in the United States.

In examining 10 years of standardized math test scores for more than 280,000 students who had over 3,000 different teachers, the researchers found a wide variation in the rate at which teachers improve their effectiveness at boosting test scores. Some teachers improve in effectiveness at a rate that is two or three times faster than others and continue such rapid gains into their 10th year of teaching.

When the test score data was combined with teacher survey results that measured teachers’ assessment of their working conditions, the researchers found that improving a school’s professional environment could accelerate teacher development. Teachers whose schools ranked in the 75th percentile on school professional environment showed greater gains in effectiveness than similar teachers working in schools that placed in the 25th percentile.

The difference was so great that by the end of 10 years teachers working in the more favorable environment improved 38 percent more than those working in less favorable settings.

Examining the data for all the teachers studied, the researchers found that working in a supportive professional environment accounted for about 30 percent of the average total improvement teachers made in their first 10 years on the job.

Kraft and Papay recommend that policymakers make the fostering of supportive professional environments in schools a key professional development strategy for teachers. They say that in contrast to a one-day, skill-related training, a supportive professional environment helps all teachers every day.

The researchers also note that their finding that teachers can continue making significant improvements into at least their 10th year on the job runs counter to claims in some studies that teachers on average make rapid gains in effectiveness during their first five years of teaching but only modest gains thereafter.

Kraft and Papay say such analyses combine measures of effectiveness for thousands of teachers in a year and mask individual differences in the rate at which teachers improve and the time period over which the improvement occurs.