Just around 25 percent of District students across all grade levels are “college and career ready” in math and English, according to the results released Tuesday of a national standardized test linked to the Common Core academic standards.

The tests, administered in the spring, showed slight overall gains citywide compared with 2015, and a persistent achievement gap between white and minority students.

Charter schools — which educate about half the public school students in the city — slightly outperformed D.C. Public Schools (DCPS). Twenty-nine percent of charter school students met or exceeded expectations on the English portion of the exam; for DCPS, 25.5 percent of students met or exceeded the standard. Twenty-six percent of charter school students and about 24 percent of DCPS students earned high marks on math.

[See all results for all schools here]

The biggest surprise came from the results at Woodrow Wilson High School, one of the city’s historically best-performing high schools, which experienced a plunge in English proficiency scores.

The computerized Partnership for Assessment of Readiness for College and Careers (PARCC) grades students on a five-point scale, with those who earn fours and fives meeting or exceeding expectations and considered “college and career ready.” Students were tested in grades three through eight and once in high school, as required by federal law.

Wilson High School in Northwest Washington experienced the worst setback — a drop of nearly 58 percent in the number of students who met or exceeded expectations on the English portion of the test. In 2015, 50 percent of Wilson students earned fours and fives in that area; this year, just 21 percent of students did.

But the school saw a bump in the number of students meeting or exceeding expectations in math, with 18 percent of students at that level in 2016, compared with 8 percent in 2015.

School Without Walls High School —a high-performing DCPS school where admission is by application — saw a 12.4 percent drop in students earning fours and fives on the English portion of the test.

It is unclear what caused the dramatic drop in these two schools. Officials suggested Tuesday that normally high-scoring students may have intentionally flubbed the test.

Schools Chancellor Kaya Henderson said that more than 100 Wilson parents unsuccessfully sought permission for their children to “opt out” of PARCC, which came the week before Advanced Placement exams and in the middle of AP review sessions.

Wilson principal Kimberly Martin said students seemed to be more focused on AP tests than PARCC. “We saw students that were finishing the exam in five or seven minutes,” Martin said of PARCC, which was given in three parts, each designed to be no less than 90 minutes long.

Of the students in the grade tested at Wilson, 68 percent took the English test and 72 percent took the math test. That was a lower participation rate than at most other high schools in the city, suggesting there might have been a modest de facto “opt out” movement at Wilson during PARCC. But that participation rate did not differ drastically from the rate in 2015, when 69 percent took the English test and 65 percent took the math test at Wilson.

Ruth Wattenberg, the state Board of Education representative from Ward 3 — where Wilson is located — said parents have complained that PARCC does not correspond to the course work students take in school.

“Not surprisingly, many of these students felt these tests were completely unrelated to what they were studying,” Wattenberg said. “There was a backlash of many students and parents who said this was ridiculous.”

Meanwhile, high-performing high schools such as Benjamin Banneker and the BASIS DC Public Charter School saw big improvements this year. At Banneker, 98 percent of students scored a four or five on the English portion — a nearly 25 percent increase over the previous year. At BASIS, 91 percent of students earned these high marks — an 18 percent increase over the previous year.

Henderson, D.C. Mayor Muriel E. Bowser (D) and charter school board officials lauded the overall improvements but warned that much work remains to be done.

“The gains are promising, but in no way are they sufficient,” Bowser said. “Some of the data suggests that we have to do more and we have to do it faster.”

[A quarter of D.C. students ‘on track’ for college, 2015 PARCC test results show]

This marks the second year that D.C. students have taken PARCC, an exam that is designed to be more challenging than previous tests administered by the District and enables the performance of D.C. students to be compared with peers in six other states, including Maryland. The test underwent significant changes between 2015 and 2106.

The scores offer a look at how District students are performing on the Common Core Standards, which were adopted by the city in 2012 and are designed to increase the depth and rigor of what is taught.

Henderson, who will be leaving her post Oct. 1, cautioned that the District could not be expected to make rapid improvements in a single year.

Black and Hispanic students in the District saw modest increases in their scores but are still underperforming compared with their white peers. Nineteen percent of black students earned a four or five on English, and 17 percent of black students earned those marks on math, up 2.3 and 2.2 percentage points, respectively. Twenty-five percent of Hispanic students earned fours and fives in English, and 22 percent earned those scores in math, up 2.9 and two percentage points, respectively, from last year. Students considered economically disadvantaged also saw an overall bump in their scores by more than three percentage points.

White students are the only demographic group that saw lower scores, and city officials attributed that to the decline in the scores at Wilson, where 1 in 4 students is white.

White students experienced a decrease of 4.8 percentage points in English results overall, and a bump of 2.7 percentage points in their math results. Still, 74 percent of white students earned fours and fives on English, and 71 percent earned that on math.

The biggest gains were seen in elementary math. Third-grade math scores increased seven percentage points, from 30 percent of students considered “college and career ready” to 37 percent.

Eighth-grade math scores, however, dropped three percentage points, from 17 to 14 percent. In English, there were slight gains in every grade except at the high school level, where the percentage of students scoring fours or fives dropped from 25 percent last year to 21 percent in 2016.

Based on these test scores, the highest performing DCPS high schools are Benjamin Banneker and School Without Walls — two competitive-application high schools.