I was struck by a recent Chalkbeat piece by a young woman who had earned a high GPA at a middle school in Harlem. Believing herself well prepared, she arrived at an elite high school only to find herself having to work hard to stay afloat in her classes.

Her A’s, it seemed, didn’t mean the same thing as the A’s from other, more affluent, schools.

As a teacher, I know that she’s right. Grades are different from school to school, district to district, and I suspect, state to state. And it presents a problem that cannot easily be solved — especially in English, the subject I teach.

The students who sit before us vary greatly. Some schools have students who are mired in poverty and who are also not fluent in English. (Some entire districts are this demographic. I taught in one for many years.) Other schools are quite affluent and have no English language learners. Guess which population demonstrates stronger academic skills?

We teachers cannot help but get normed to our population. We get used to seeing what we always see. Since an A is “excellent,” we tend to give A’s — really, all grades — in relation to the population with which we work. To get an A in any school means that the student is doing an excellent job relative to their peers.

When I taught in my old middle school, most kids arrived below grade level in math and English, and some were several years below. We became so used to seeing below-grade-level work that it became our “normal.” When an eighth-grader who came to us at a third-grade level turned in four or five pretty good paragraphs on a topic, we were elated.

That kid has come so far! We would bring that assignment out at the next department meeting and crow about her success. And we would award an A, because she did an excellent job in relation to her peers.

The trouble is, you take the same assignment down the highway 10 miles to an affluent school, and that same paper would earn a C-minus. Their eighth-graders came to them using strong theses, well developed points, and embedded quotations. To get an A in that school, the student has to do an excellent job relative to much more accomplished peers.

Kids who are just learning English, who are homeless or move frequently, who could be food-insecure, don’t have those skills. They’re not incapable of developing those skills. But they are unlikely to have them yet because of the challenges they face.

I now teach students in a highly competitive magnet program in another state (600 applicants for 150 seats, to give you an idea). Now I am normed so far the other way, it makes me dizzy. These students have skills that I never dreamed any eighth-grader could possess. The eighth-graders I taught this year wrote at a nearly professional level. Many of them score in the 99th percentile nationwide for both math and English.

Now I realize that, in my old district, we almost never saw a truly advanced student. In fact, not only had most of us never seen an advanced paper, we rarely saw any paper that was above partially proficient, even from students we thought were working above grade level.

The reality is that if we truly tried to hold everyone to the same bar, we would see even more troubling patterns emerge.

We would see the good grades going to rich white kids, those who get museums and vacations and Starbucks in the summer, and we would see the failing grades go to the poor kids — entire schools, even districts, full of poor kids who aren’t good with English and who spend their summers in front of the TV while mom and dad work.

So we have these very different sets of standards, even with the Common Core. There is a faction who would say this is “the soft bigotry of low expectations” that George W. Bush talked about. I say this shows that socioeconomic status and students’ home lives are the major predictors of success in school, and that the bigotry that causes that is real.

What does all this mean for the student who wrote the original piece about her transition to high school? What it means for her, immediately, is she sees firsthand the vast differences in preparation and opportunity between the socioeconomic classes. In the long term, it could mean a lot as far as college choices go. I don’t think we know yet how to really solve this problem.

We as a society need to address the factors that limit access and equity for poor and minority children. Leveling that particular playing field may be the most important charge with which educators are tasked.

Mary Nanninga is a middle school English teacher in Montgomery County Public Schools in Maryland. She previously taught in Westminster Public Schools in Westminster, Colorado.