The state Department of Education has given each of Maine’s 600 public schools a letter grade, from A to F, and today those rankings will be made public.

Just as an individual child’s report card is designed to give parents an indicator of that student’s progress, school grades — at least as touted by state education officials — are meant to provide a community with a benchmark of their school’s success.

The goal is to offer “a snapshot of where their school is at,” an Education Department spokesman told the newspaper. These snapshots, however, leave more out of the picture than they include.

A system that assigns each school a single letter grade is hardly capable of reflecting the mix of elements that affect student performance, including the community’s economy, school funding and access to early childhood education.

This approach doesn’t tackle the causes of low rates of student success, it just records the symptoms.

Factor in a state chief executive who consistently disparages public school educators and administrators — “If you want a good education, go to a private school,” Gov. Paul LePage said last fall — and the chances for positive change are slim to none.

The A-F system assesses each school based largely on its students’ performance on standardized tests. Kids from poor neighborhoods or communities consistently lag their peers from wealthier areas, where students have higher standardized test scores. So don’t expect to see many surprises on the list of schools with A or B rankings.

The lower-scoring schools, meanwhile, will have few resources to help their students catch up.

The Department of Education has all of $3 million set aside to help schools develop improvement plans, but this allocation hardly makes up for the LePage administration’s failure to fund education adequately. (Neither LePage nor his predecessor, John Baldacci, has ever carried out a 2004 voter mandate for the state to fund 55 percent of the cost of education.)

Under LePage, preschool and child care spending also has taken a hit, leaving students from low-income families at a disadvantage. These youngsters need the boost that early childhood education can give. Without it, they likely will start kindergarten less prepared than others.

And they don’t have a lot of time to catch up: Research shows that youngsters have only a few years to develop the basic skills needed for academic success.

The A-F ranking system won’t tell Mainers anything they’re not aware of already. They know that schools in poor communities are hurting; they also know that the state isn’t willing to use a lot of its resources to help.

To demand progress under these circumstances is a test some schools are set up to fail.