Beyond the potential effects of tracking, children from wealthy families seem to benefit from many variables outside the classroom, including enriching home environments, safe neighborhoods, good childcare, after-school activities, and the education level of their parents. Highly educated parents in these towns seem to have a “heightened focus” on education, Reardon said, and they are increasingly willing to spend resources to ensure that their children are academically successful. While less-educated parents certainly want their own children to do well, they tend to have less disposable income. Because white parents are more likely than parents of color to be highly educated and to earn more, white children are more likely than their peers of color to have access to enriching educational experiences outside of the classroom.

“I’m not really surprised,” said Sonja Brookins Santelises, the vice president of K-12 policy and practice at the nonprofit Education Trust and the former chief academic officer for Baltimore City Public Schools. Families with means, she pointed out, are spending more than they used to on experiences outside the classroom that can increase test scores for their kids. This leaves children from lower-income families struggling to catch up.

A child who grows up in an affluent home with professors for parents in Berkeley, for instance, is more likely to be enrolled in activities like ballet and soccer than a child in Berkeley whose parents don’t have as many resources. According to the Pew Research Center, 84 percent of families who earn at least $75,000 say their children are involved in sports, and 62 percent say their kids take music, dance, or art. For families earning less than $30,000, those participation rates fall to 59 percent and 41 percent, respectively. The child from the affluent family is also more likely to have parents who can assist with homework and who have the financial ability and time to take trips to museums or galleries on weekends—out-of-school activities that research suggests boost in-school test scores.

Studies suggest that music lessons can help with everything from reading to spatial reasoning, and the College Board found that students who took art and music throughout high school scored higher on the SATs than students who did not. A research paper from the National Endowment for the Arts suggested that eighth graders who were engaged in the arts throughout elementary school tested better in science and writing than their peers who were not involved in the arts.

While the recession and the arrival of No Child Left Behind prompted many schools to scale back such activities to focus on the subjects students are evaluated on, Brookins Santelises says the cuts have damaged student engagement, and likely widened achievement gaps in the process. Her daughters learned more about the American Revolutionary War during a short family trip to Philadelphia than they did in a classroom lesson on the topic, she said. But not all kids have parents who can take them to visit Independence Hall. For that reason, Brookins Santelises said, it’s more important than ever for schools with increasingly diverse student bodies to consider whether they’re offering students a range of learning experiences, from music to museum field trips, to expose children to lessons they might not get at home and to spark excitement about learning. She thinks doing so can have a positive impact on scores, but said that a recent emphasis on testing in schools has some educators zeroing in on test prep at the expense of field trips and art lessons. “What we end up doing,” she said, “is giving kids who are living in poverty the most impoverished learning experiences.”