Denver Public Schools has joined a group of big-city school districts whose scores on the biennial tests known as “the nation’s report card” will be reported separately from state-level scores for the sake of comparing the urban districts to one another, it was announced Tuesday.

The National Assessment of Educational Progress, or NAEP, tests will next be administered in 2017 to a sample of fourth and eighth grade students in every state.

In DPS and 26 other large urban districts, an “oversampling” of students will be tested. Officials who administer NAEP did not say how many more DPS students will be tested, but it will not be every student. Each student who participates will spend an hour taking either a reading or math test.

The results from those big-city districts will be reported as part of the Trial Urban District Assessment program, which started in 2002 with just five cities. The idea was to further mine the data provided by NAEP, a long-running assessment considered by many to be the gold standard in standardized tests, which previously just reported state-level results.

“Cities wanted to be able to compare themselves across state lines with other big-city school districts that shared many of the same issues and challenges,” said Michael Casserly, the executive director of the Council of Great City Schools, which first suggested the idea.

“We wanted to be able to tell whether or not the reforms we were pursuing were producing results,” Casserly added. With different districts trying different reform strategies, comparing results was one way to tell which were working and which weren’t, he said.

“NAEP gave us data at a level of detail across state lines that we couldn’t get any place else.”

Participation in the urban district program is voluntary. To be eligible, districts must be located in cities with populations of at least 250,000 people and half of the students they serve must either be minorities or qualify for free or reduced-price lunch, a proxy for poverty.

Colorado already participates in another testing consortium called PARCC that’s meant to make it easier to compare student scores across states. Unlike NAEP, the PARCC tests are annual and mandatory for all state students in grades three through nine. But the number of states in the consortium is shrinking and the way each state scores its tests can differ, making the comparisons less useful.

“Given the decrease in the number of PARCC states, and the lack of comparable districts in Colorado, DPS was interested in seeing how we compare to other large urban districts throughout the country,” district officials said in a statement.

Students in urban school districts tend to score lower than the national average on NAEP reading and math tests. But data from the past 12 years shows that big-city school districts are narrowing that gap. In addition, results show that the reading scores of some black and Latino boys in urban districts have improved more than the scores of black and Latino boys nationwide.

The urban district comparisons have revealed two ingredients necessary to improve student achievement, Casserly said: Programs that improve the quality and rigor of classroom instruction, and a district leadership team united around a common agenda.

“In many ways, Denver has a lot of these … strategic and tactical things in place,” he said, “and I’m going to be very, very interested to see how they do.”

The NAEP tests were last administered in 2015. Colorado’s scores declined but stayed above national averages.