The SAT or ACT is hardly the first time that students encounter standardized tests. By the time today’s kids complete high school, they’ll have sat through dozens. But testing in K-12 education, often mandated by the government, has a broader purpose than college admissions tests. It’s about assessing students not just as individuals, but as a population, along with their teachers, schools and districts.

During the pandemic, that information is even more important, says Morgan Polikoff, a professor of education policy at the University of Southern California. “We need to know how the pandemic has affected students,” he says. And it’s likely, he adds, that the education of students of color and those in urban areas, where distance learning persisted for the longest, suffered in an outsized way during the 2020-21 school year.

But it’s impossible to be sure. In the spring of 2020, the US Department of Education waived the requirement for states to conduct annual tests. The every-other-year National Assessment of Educational Progress, originally slated for 2021, has been postponed.

Fall 2020 assessments by the nonprofit Northwest Evaluation Association, covering nearly 4.4 million elementary and middle school students, found that kids were behind in math, but still progressing in reading. But there’s a caveat: About one in four students didn’t show up for the tests, including many from minority or low-income populations.

“We don’t know the full learning loss,” says Matthew Pietrefatta, CEO and founder of the tutoring and education company Academic Approach in Chicago.

Eric Grodsky, a sociologist at the University of Wisconsin–Madison, thinks that missing those tests will be a huge problem going forward. “You need tests to tell you how bad the problem is, and you need tests to spec out how you’re going to resource schools and families.”

Clarity may be forthcoming: The Biden administration required most public schools to perform their annual assessments for the 2020-21 school year, although it permitted shorter or remote examinations.

This article is part of Reset: The Science of Crisis & Recovery, an ongoing  Knowable Magazine series exploring how the world is navigating the coronavirus pandemic, its consequences and the way forward. Reset is supported by a grant from the Alfred P. Sloan Foundation.