Seattle ? What do teachers want?

Supportive principals more than higher salaries.

Digital media more than textbooks.

Evaluations based on how much their students learn, rather than principals’ observations.

Those are a few findings from what’s thought to be the largest-ever survey of American public-school teachers, sponsored by the Bill & Melinda Gates Foundation and the Scholastic publishing company.

Over the phone and online, about 40,000 teachers answered questions about what they need to help more students achieve, and what they think about issues such as merit pay, testing and common learning standards.

The results offer a rich look at the challenges and frustrations of teachers and underscore how deeply many care about their work. Seven out of 10, for example, reported that they attend student events at night or on weekends.

For the Gates Foundation, the goal was to highlight teacher opinions on how best to improve the nation’s schools — a debate taking place in school districts and state capitols across the nation.

“We wanted to put teacher’s voices front and center in the debate around education reform,” said Vicki Phillips, the Gates Foundation’s education director. “Teachers are on the front line of this work every day … it doesn’t make sense not to be talking to teachers.”

Harris Interactive conducted the survey from mid-March through mid-June last year. Teachers weren’t told who sponsored the survey.

Other highlights of the national results:

• While 92 percent of teachers said tests given in class are essential or very important in measuring student achievement, just 27 percent said the same about state standardized tests.

• Just 22 percent said they thought evaluations by principals were a very accurate measure of their work.

• Less than half said higher salaries are absolutely essential for keeping good teachers, and only 8 percent said they thought pay for performance is vital.

• Forty percent said students entered their classroom below grade level.

• Nearly 60 percent said common learning standards in all states would have a strong impact on student achievement.

• Just 12 percent strongly agree that traditional textbooks engage students, while 44 percent said the same about digital resources such as classroom technology.

• When asked what’s most important in keeping good teachers, the top choice was “supportive leadership” followed by higher salaries.

• Close to a third — 30 percent — said monetary rewards for teachers had no impact on increasing students’ academic achievement.

• All but 3 percent of teachers said that setting high expectations is very important or essential in raising their students’ achievement.