More evidence emerged this week that online school is taking its worst academic toll on Virginia’s most vulnerable students, as superintendents in the state — facing mounting pressure to reopen schools — took tentative steps toward in-person instruction.

Loudoun County Public Schools went the furthest, welcoming back more than 7,300 elementary school students this week. Other Northern Virginia districts are moving more slowly: Arlington Public Schools said it would return thousands of elementary and middle school students early next year, while Alexandria City Public Schools outlined plans to send some students with disabilities and English-language learners back into school buildings in late January — followed in early February by kindergartners through fifth-graders.

These developments come as schools in the D.C. region, and nationwide, are beginning to gather and publish data on students’ grades for the first full semester of online learning. Early analysis highlights steep drops in academic performance among low-income students and children of color in the Washington area.

Last week, Fairfax County Public Schools — the state’s largest district, with 186,000 students — reported that the percentage of children earning at least two F’s rose by 83 percent this semester, with the largest increases observed among students with disabilities, English-language learners and Hispanic students. On Thursday, Maryland’s largest school district, Montgomery County Public Schools, revealed that failing grades in math and English have increased as much as sixfold among Black and Hispanic students living at or near the poverty line.

Also on Thursday, Arlington Public Schools — which enrolls 26,000 in Northern Virginia — published early data on young students’ literacy levels. Results of the Phonological Awareness Literacy Screening, known as PALS, showed that the percentage of kindergartners, first-graders and second-graders meeting literacy benchmarks dropped slightly, by single digits, for every age group.

But the declines were far steeper for Black and Hispanic students and English-learner students. The percentage of Hispanic K-2 students achieving the benchmark dropped by more than 13 percentage points this year, to 61 percent, while the percentage of Black students hitting the mark dropped by more than eight points to 79 percent.

The percentage of English learners, meaning children who speak another language at home and are learning English at school, dropped even more precipitously. Just 21 percent of first-grade English learners met the literacy benchmark, although 46 percent of that group had done so last academic year. Similarly, 45 percent of second-grade English learners hit the mark, compared with roughly 74 percent of that group last year.

“It is evident that we’re continuing on a downward trend,” Superintendent Francisco Durán told the school board at a virtual meeting Thursday. “Our greatest concern here continues to be the performance of Black and Hispanic students . . . and for our English learners, that’s probably one of the most alarming bits of data you’ll see.”

In the immediate future, he said, the school system will attempt to fight the trend by doubling down on small-group literacy instruction, whether in-person or virtual. He noted that Arlington plans to conduct a full-bore analysis of first-quarter grades, and how they compare with marks achieved in years past, for students of all grades later this month.

And officials have formed a “Distance Learning Task Force,” Durán announced Thursday. The group is charged with addressing “concerns related to students’ academic performance and social-emotional growth during distance learning,” according to the presentation, and will start its work in January.

News of students’ flagging academic performance has spurred some mothers and fathers to even greater anger over the continued shutdown of most major school systems in Northern Virginia. School systems in Loudoun County, Fairfax County, Arlington and Alexandria city have been largely shuttered since March.

This week, an especially irate group of parents in Fairfax — who call themselves “OpenFCPS” — sent a letter to the school board urging members to fire Superintendent Scott Brabrand over what they call his failure to reopen schools.

Fairfax had returned several thousand students to classrooms over the course of the fall, prioritizing students with disabilities and English-language learners, as well as very young children. But last month, as cases spiked in the Washington area, Brabrand halted plans for further returns and sent more than 3,000 students back to online-only instruction.

This came as welcome news for some employees at W.T. Woodson High School, which had reopened for students last month and subsequently saw sufficient coronavirus infections to qualify as an “outbreak of COVID-19,” according to the Virginia Health Department, which is tracking cases in school settings statewide.

As of Nov. 27, Woodson is the only school in Fairfax County to have suffered an outbreak. There is so far little evidence that reopened schools in Virginia have served as superspreader sites.

Still, the experience of a handful of staffers in one Special Education department at Woodson shows the potential risks of an in-person return. Fourteen employees in that department came back to the building on Oct. 26, staffers wrote in a later letter to the school board; within eight days, four of them had tested positive for the virus.

So did another staffer in “an adjacent department [and] 1 out of only 20 students,” the staffers wrote in the letter, dated Nov. 24. The staffers attributed the infections to lapses in safety measures, including a failure of some students to wear masks, violations of social distancing, ventilation problems and insufficient personal protective equipment.

“We were provided with gloves and hand sanitizer, but not all staff members received masks, and some only received one disposable mask for two weeks of in-person work,” the letter states. “The result of these violations for our department have been devastating.”

In a statement, Fairfax spokeswoman Lucy Caldwell said the school system carefully investigated each of these concerns and offered additional protective gear to the letter’s signatories, while also allowing them an opportunity to ask questions and request “any supports they felt were needed.” She also said Fairfax officials followed all appropriate protocols in notifying families and employees of potential exposure at Woodson.

“Due to the small number of students and staff involved, to protect the confidentiality of individuals involved, we are unable to provide additional details,” Caldwell said in the statement. “Our data, at this point, indicates that the vast majority of cases of COVID are acquired in the community and there is very low transmission in schools.”

Neighboring Alexandria City Public Schools, which enrolls 16,000, is also running up against staffer resistance to return-to-school plans. At a virtual board meeting Thursday, Superintendent Gregory C. Hutchings Jr. announced the results of a recent survey of employees: Forty-five percent had reported “an inability to return” to face-to-face teaching.

The most popular reason was “Fear/Anxiety,” cited by 43 percent of Alexandria’s 1,178 staffers — although only 12 percent of the group cited that reason alone. Other commonly selected reasons included “Underlying Medical Conditions” and “Caring for a family member.”

At the meeting, board member Jacinta Greene (District A) questioned Hutchings about the 12 percent who reported that fear and anxiety were the only things barring them from going back inside classrooms. She wanted to know the school system’s plans for those employees.

Hutchings said he is “in the process” of reaching out to that group, which numbers about 70 people total, to discuss their concerns. He asked one of his top staffers, also present on the board’s Zoom call, to explain that Alexandria as an employer is legally required to provide a safe workplace.

The superintendent also outlined a program for gradually returning students to classrooms over the next several months. Under the schedule, some students with disabilities in kindergarten through second grade will return on Jan. 19. By Jan. 26, that group would expand to include students with disabilities and English learners in kindergarten through fifth-grade.

On Feb. 2, Alexandria hopes to return students with disabilities and English learners enrolled in grades 6 though 12. And on Feb. 9 and Feb. 16, respectively, the school system aims to send back all remaining students in prekindergarten through fifth grade, followed by all students in sixth through 12th grade. Still, any family that prefers to do so can keep their child home for all-virtual learning.

Almost alone among Northern Virginia school systems, Loudoun is moving ahead with its return-to-school plans. The school system sent roughly 7,300 third-, fourth-and fifth-graders — as well as roughly 200 high-schoolers enrolled in the Academy of Science and the Academy of Engineering and Technology — into classrooms on Tuesday.

They joined roughly 10,000 of their peers who already headed back this fall, including thousands of kindergartners, first-graders and second-graders, as well as students with disabilities and English learners.