Opinion

Mike’s murky marks

Michael Bloomberg wants history to judge his mayoralty based, in large part, on what he did for the city’s schools. But his system for grading those schools is eroding confidence in his leadership.

The problem: The grades — for too many schools — are just too confusing.

This year’s marks, or “progress reports” — released last week for some 1,200 elementary and middle schools — prove the point yet again.

For example, schools in District 2, which includes well-off sections of TriBeCa and the Village, are widely considered among the best in the city.

But the district’s year-on-year ranking, based on the progress reports, nose-dived from 4th among the city’s 32 districts — to an embarrassing 12th. That includes PS 234, a particularly well-respected school, whose overall grade dropped from an A to a C.

It didn’t help that rankings released by the state less than two months ago, which reflected slightly older data, appeared to be at odds with the city’s grades for many schools.

Likewise, of seven elementary and middle schools that Bloomberg says are so bad they should be shut down and reopened with new staff, two wound up with Bs.

How is that possible? Actually, there is an explanation: A high grade from the city, you see, doesn’t necessarily mean a school is truly good — nor does a low grade mean it’s bad.

That’s because the grades largely measure student “progress” — not actual performance.

And therein lies much of the problem: Many parents have little understanding of what the grades actually mean.

So when they see their kids’ beloved schools graded poorly, even as the students there earn reasonably high scores on tests, they just figure that the Bloomberg folks are ninnies.

That erodes confidence in the mayor’s management — endangering his legacy and undermining respect for vital reforms, like mayoral control of the schools.

Yes, many grades, especially at the high and low ends, do correspond roughly to what folks think the schools deserve.

It’s also worth noting that the grading system stems from a vital effort to make schools accountable. If parents get mad at a low grade, they may pressure the school. That’s a good thing.

But then, if folks don’t trust the grades in the first place, accountability measures have no chance.

Nor, for that matter, do Bloomberg’s reforms — or the schools themselves.