It has become both common and tiresome to hear some politicians, such as Mayor Bloomberg, blame teachers and teachers’ unions for any problems in the public schools.

The good news is that the public doesn’t buy it.

A new poll shows that 72 percent of Americans trust the nation’s public school teachers. Among people under 40, the number trusting teachers is even greater — 78 percent, according to the 45th annual survey of public attitudes toward schools by Phi Delta Kappa and Gallup, the longest-running poll of its type.

Just as the public’s faith in teachers has held strong, their confidence in their local public schools has increased. The poll found that 53 percent of Americans would give their local schools an “A” or “B,” up from the 48 percent who would have given high grades to their community’s schools a decade ago.

It is reassuring to know that Americans are too smart to be taken in by destructive political rhetoric about teachers and our schools.

The poll contained some other encouraging findings on public views of education.

A growing number of people are against diverting taxpayer money to fund private schools: 70 percent of those surveyed oppose private school vouchers, a sharp increase from 55 percent a year ago.

It is also positive that few people are buying into the standardized test mania that has overtaken many schools over the last 12 years. The survey found that fewer than 25 percent of Americans believe the increased testing has improved schools.

A less encouraging, though unsurprising finding is that most Americans, nearly two-thirds, know little to nothing about the Common Core Learning Standards that have been adopted by nearly all states, including New York, and are expected to lead to sweeping changes in curricula around the country. Clearly, federal, state and local education officials need to do a better job of educating the public about this initiative.

But, for now, teachers can take heart as they begin a new school year. Anti-teacher and anti-union politicians may whine and complain. But most members of the public are tuning them out.