Whenever "Gina," a fifth-grader at a suburban public school, did her math homework, she never had to worry about whether she could get help from her mom.

"I help her a lot with homework," Gina's mother, a married, mid-level manager, explained to us during an interview for a study we did about how teachers view students who complete their homework versus those who do not.

"I try to maybe re-explain things, like, things she might not understand," Gina's mom continued. "I understand that Gina is a very visual child but also needs to hear things, too. I know that when I'm reading it, and I'm writing it, and I'm saying it to her, she comprehends it better."

One of us is a sociologist; the other is a math education professor. We were curious about how teachers reward students who complete their homework and penalize and criticize those who don't — and whether there was any link between those things and family income.

By analyzing student report cards and interviewing teachers, students and parents, we found that teachers gave good grades for homework effort and other rewards to students from middle-class families like Gina, who happen to have college-educated parents who take an active role.

But when it comes to students such as "Jesse," who attends the same school as Gina and is the child of a poor, single mother of two, we found that teachers had a more bleak outlook.

The names "Jesse" and "Gina" are pseudonyms to protect the children's identities. Jesse can't count on his mom to help with his homework because she struggled in school herself.

"I had many difficulties in school," Jesse's mom told us. "I had behavior issues, attention-deficit." Jesse's mother admitted she still can't figure out mathematical division to this day.

"Sometimes you just feel stupid,“ Jesse’s mom said. ”Because (my son)'s in fifth grade. And I should be able to help my son with his homework in fifth grade."

Unlike Gina's parents, who are married and own their own home in a middle-class neighborhood, Jesse's mom isn't married and rents a place in a mobile home community.

As a matter of fairness, we think teachers should take these kinds of economic and social disparities into account in how they teach and grade students. But what we found is that they usually don't, and instead seem to accept inequality as destiny. Consider, for instance, what a fourth-grade teacher — one of 22 teachers we interviewed and observed during the study — told us about students and homework: "I feel like there's a pocket here — a lower income pocket. And that trickles down to less support at home, homework not being done ... If they don't have the support at home, there's only so far I can take them. If they're not going to do their homework, there's just not much I can do."

While educators recognize the different levels of resources that students have at home, they continue to assign homework that is too difficult for students to complete independently, and reward students who complete the homework anyway.

Consider, for example, how one seventh-grade teacher described his approach to homework

"I post the answers to the homework for every course online,“ he said. ”The kids do the homework, and they're supposed to check it and figure out if they need extra help. The kids who do that, there is an amazing correlation between that and positive grades. The kids who don't do that are bombing.

"I need to drill that to parents that they need to check homework with their student, get it checked to see if it's right or wrong and then ask me questions. I don't want to use class time to go over homework."

The problem is that the benefits of homework are not uniformly distributed. Rather, research shows that students from high-income families make bigger achievement gains through homework than students from low-income families.

This relationship suggests that homework may contribute to disparities in students' performance in school.

Research also reveals that making sense of the math homework assigned in U.S schools is often more difficult for parents who have limited educational attainment, parents who feel anxious over mathematical content. It is also difficult for parents who learned math using different approaches than those currently being taught in the U.S.

Meanwhile, students from more-privileged families are disproportionately more likely to have a parent or a tutor available after school to help with homework, as well as parents who encourage them to seek help from their teachers. And they are also more likely to have parents who feel entitled to intervene at school on their behalf.

In the schools we observed, teachers interpreted homework inequalities through what social scientists call the myth of meritocracy. This myth suggests that all students in the U.S. have the same opportunities to succeed in school and that any differences in a student’s outcome are the result of, or lack of, effort. Teachers in our study said things that are in line with this belief.

For instance, one third-grade teacher told us: "We're dealing with some really struggling kids. There are parents I've never even met. They don't come to conferences. There's been no communication whatsoever. … I'll write notes home or emails; they never respond. There are kids who never do their homework, and clearly the parents are OK with that.

"When you don't have that support from home, what can you do? They can't study by themselves. So if they don't have parents that are going to help them out with that, then that's tough on them, and it shows."

Jessica Calarco is an associate professor of sociology at Indiana University. The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.