For more than a decade, standardized-test scores have been the dominant metric for measuring what public-school students know and are able to do. No Child Left Behind, the sweeping federal education law enacted in 2002, ushered in a new era of student testing and school compliance. And in the years that followed—to meet targets and avoid sanctions—education leaders at the local and state levels have sought a variety of ways to boost students’ performance on tests, including extending the school day and giving bonus pay to teachers based on students’ test scores. Even less conventional methods, such as banning cell phones and offering yoga-like exercises, emerged as school administrators pursued the holy grail of high standardized-test scores.
But according to a new study, there’s one option that may have been overlooked: the ubiquitous school lunch. As detailed in a recent paper, economists set out to determine whether healthier school lunches affect student achievement as measured by test scores. The intense policy interest in improving the nutritional content of public-school meals—in addition to vendors’ efforts to market their school meals as good for the body and the mind—sparked the researchers’ curiosity and led to an unexpected discovery: Students at schools that contract with a healthier school-lunch vendor perform somewhat better on state tests—and this option appears highly cost-effective compared to policy interventions that typically are more expensive, like class-size reduction.
“When school boards are going out and contracting with these vendors, what they're thinking is that they're going to improve the health of the students, that they'll get them to eat healthier. I don't think they're thinking of it as a tool to actually improve academic performance [but] we found that it is,” said Michael L. Anderson, an associate professor of economics at the University of California, Berkeley, and one of the study's co-authors. “Something that is basically cheap, that is going to improve student health, and that has test-score gains seems like it would be very attractive [to] policymakers.”
According to Anderson, who spoke as school meals received renewed attention due to President Trump’s proposed budget, this is the first large-scale study to examine how the overall nutritional quality of school meals affects student test-score achievement. In 2010, as part of a push to combat childhood obesity, the Healthy, Hunger-Free Kids Act was passed, resulting in more rigorous nutrition standards for school cafeterias. There is a body of recent literature that suggested a link between school meals and student test scores, but that research focused on improving access rather than the meals’ nutritional value.
To determine the link between food quality and student achievement, Anderson and his colleagues collected data from the California Department of Education on school districts’ meal vendors for the academic years from 2008-09 to 2012-13. Over that five-year period, 1,192 schools—about 12 percent of California public schools, including public charter schools—contracted for at least one school year with an outside company to provide lunch.
The team then hired the Nutrition Policy Institute, a research unit housed at the University of California, to score the nutritional content of vendors’ school lunches. Armed with sample school-lunch menus, NPI calculated the Healthy Eating Index (HEI), a U.S. Department of Agriculture measure of dietary quality for food items, for all of those companies’ meals. The average HEI score among all vendors with menu information was tabulated, and vendors with above-median scores were classified as healthy school-lunch providers. But there was still one crucial piece of information missing: how students at schools with healthy vendors stacked up against their peers at non-vendor schools on state tests.
In pursuit of that answer, the study’s authors compiled a database covering the same five-year timespan with school-by-grade-level test results on California’s Standardized Testing and Reporting exam, a statewide test given at the time to all public-school students in grades 2 through 11. Test score data from some 9,700 elementary, middle, and high schools found that contracting with a healthy meal vendor correlated with increased student performance by between .03 and .04 standard deviations—a statistically significant improvement for economically disadvantaged and non-disadvantaged students, Anderson said, adding that the size of the effect “is not huge … but it is notable.”
What’s more, he said, districts are almost getting these improvements free of charge. After tabulating the average price per meal in the vendor contracts—and estimating the cost of in-house school meals based on National School Lunch Program reimbursements—the study found that it cost about $222 per student per year to switch from in-house school-lunch preparation to a healthier lunch vendor that correlated with a rise of 0.1 standard deviations in the student’s test score. To put that statistic into perspective, healthier meals could raise student achievement by about 4 percentile points on average.
In comparison, it cost $1,368 per year to raise a student’s test score by 0.1 standard deviations in the Tennessee STAR experiment, a project that studied the effects of class-size on student achievement in elementary school. The paper notes that established research in the field supports the need for “lower-cost policies with modest effects on student test scores [that] may generate a better return than costly policies with larger absolute effects.”
Sean Patrick Corcoran, an associate professor of economics and education policy at New York University’s Steinhardt School of Culture, Education, and Human Development, said the study underscores the positive impact of schools serving healthier meals, and he seconded the authors’ conclusions regarding cost-effectiveness. “I've seen a number of other rigorous studies that also find a connection between healthy eating and academic performance,” he said. “Students who eat regular, healthy meals are less likely to be tired, are more attentive in class, and retain more information.” And he said some effects are almost immediate: “Even when schools serve calorie-rich food on test day, students perform better on those tests.”
In Oakland, California, Kweko Power, 15, a sophomore at Oakland High School, agreed that there’s an academic benefit to healthier meals—citing classmates who skip school lunch because it’s unhealthy and unappealing—but she believes the benefits extend beyond test scores. “When students eat healthier and better food, they get more stamina because their body doesn't have to work as hard to process what they’re eating,” she said. “When you eat and feel good, you [are] happier … and feel less cranky. While I am usually upbeat around people, I can't be myself without good food.”
For children living in areas of concentrated poverty like Oakland, good food like fruits, vegetables, and whole grains can be hard to come by. A secondary finding in the study was that contracting with a healthy lunch provider showed no evidence of reducing student obesity. And Power’s personal experience helps explain why. “In my neighborhood, we have a Lucky's [grocery store] nearby but it's expensive … it's cheaper to go to the three liquor stores that are within five blocks of that Lucky's,” she said. “When there are liquor stores that sell cheaper and unhealthier food, families tend to opt for cheaper food; they have no other choice. In areas where youth don't have access to healthier food options, you'll tend to see more obesity.”
Power, a student leader with Californians for Justice, emphasized that test scores aside, access to healthier food is fundamentally an issue of equity and civil rights. “It's also important to look at stress levels and what contributes to stress for students,” Power explained. She said hunger and lack of proper nutrition are everyday worries for low-income students. “Without good food, students are just stressed at school, and then still stress about being expected to perform well. Having healthy school meals is really related to how the school system is serving students that don't have [much access and availability] to resources.”
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