Public schools across Long Island and other metro area suburbs already are winning high grades — and they’ve barely begun opening their doors.

Results of a back-to-school poll by Phi Delta Kappa, a global organization of professional educators, found that suburban respondents gave their local schools significantly higher marks than did residents of New York City or the nation as a whole.

Fifty-nine percent of residents in Nassau, Suffolk and other suburban counties gave schools in their communities grades of either A or B, compared with 37 percent of New York City residents. The national figure was 49 percent.

Other New York counties included in the survey were Westchester, Rockland, Orange, Putnam and Dutchess, all in the lower Hudson or mid-Hudson regions.

Public schools in upstate New York fared equally well, with 59 percent of residents surveyed there also handing out A or B ratings.

The poll, the organization’s 49th annual national survey of public attitudes toward education, drew responses from 1,588 adults, with a margin of error of plus or minus 5 percentage points for the full sample. It was conducted by the Manhattan-based firm of Langer Research Associates.

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Long Island educators frequently attribute the popularity of their schools to enriched program offerings — for example, Advanced Placement courses, science research classes and foreign language instruction in elementary grades.

“Long Island, I believe, is a definite lighthouse for cutting-edge educational programs,” said Hank Grishman, superintendent of Jericho schools, which score consistently high in national rankings. “That’s why you see groups from out-of-state frequently visiting to see what the secret sauce is in our research programs.”

Jericho resumes classes Tuesday, the first of the Island’s 124 public school systems to do so. Four other districts in Nassau County also open this week, followed by 119 districts in the region next week.

This year’s Phi Delta Kappa poll added breakdowns for two states, New York and Georgia. One purpose was to compare public attitudes toward schools in two large cities, New York City and Atlanta, with attitudes in their surrounding suburbs and in their respective states.

Upstate New York and its downstate suburbs edged out suburban Atlanta, where 57 percent of residents polled gave their schools A’s and B’s — though the difference was not statistically significant. Atlanta’s suburbs outdid their urban center, at 36 percent, as well as the rest of Georgia, at 47 percent.

New York City, for its part, had some reason to celebrate last week when the state released test scores showing that city schools for the second year in a row surpassed state averages in reading performance.

Mantell Will, a spokesman for New York City schools, responded to Phi Delta Kappa’s survey with an upbeat statement: “New York City graduation and college enrollment rates are at record highs, dropouts are at a record low, and there’s now a free, full-day, high-quality pre-K seat for every four-year-old,” Will said. “We’ll continue to work with families and communities to build on our progress, and put every child on the path to college and careers.”