Montgomery County leaders are taking steps to add mental health to the list of valid reasons to be absent from school, saying the move is especially important after the inordinate toll of the pandemic.

The change would begin in the fall, when students in Montgomery County are expected to return to full-day in-person classes five days a week. A majority of students in the state’s largest school system have been learning virtually during the past 14 months.

“Student mental health has been a challenge this year, through the pandemic, and we believe it is a wise decision,” Patricia O’Neill, a school board member, said as she introduced the change at a meeting Tuesday.

Experts and advocates have warned for months of a simmering mental health crisis as students across the nation have struggled with depression, anxiety, isolation, family hardships, sick relatives and plunging grades since schools closed in March 2020.

Under a measure unanimously approved, the board requested the superintendent of schools to revise regulations to include student “well-being” beside a mention of “student illness” as an excused form of absence.

The phrasing was selected to avoid any worries that families may have about mental illness stigma.

Board member Karla Silvestre said that the value of the change was clear, recalling an overly stressful day for her own child, when her daughter stayed home from school, and Silvestre struggled to write the school a note about her absence.

She said that her daughter was not sick and that she did not want to lie.

With the change, Silvestre said, she could simply write, “ ‘She’s not well today,’ and that would be fitting with what’s allowed.”

The idea to focus on attendance rules began with student board member Nick Asante, who introduced a measure last September asking a board committee to explore the possibility of excused mental health days.

Asante said in an interview that he had heard from many other students — on Instagram, in virtual town halls, during conversations — that mental health was a serious issue and that the school system was not giving it enough attention, “especially with the pandemic and covid-19.”

The change would give their struggles greater priority and mean a lot to a lot of students, Asante said.

When the committee took up the issue in March, it garnered support.

Board member Rebecca Smondrowski recalled Tuesday that the committee members had agreed that “if you don’t feel well, you don’t feel well, whether that’s mind, body or soul.”

The committee considered the possibility of recommending a “mental health day” each semester, or year, for every student. But members decided to broaden the definition of excused absence to better accommodate individual student needs. Parents must write a note, as with other types of absences.

In neighboring Prince George’s County, attendance procedures allow students one excused absence per semester for mental health needs, said spokeswoman Meghan Gebreselassie.

As in other school systems, officials in Montgomery County have been working on ways to improve supports for students in school. Each school has a “well-being team,” expected to continue beyond the pandemic, O’Neill said.

Montgomery school officials said nearly 400 crisis center referrals were made this school year.

Last summer, a school official confirmed that three students had died by suicide during the early months of the pandemic.

Preliminary data for 2020 shows 10 suicides were reported for people ages 24 and under, an increase from eight suicides in 2019, said Mary Anderson, spokeswoman for Montgomery County’s department of health and human services. For people under 19, the county usually has two to eight suicides a year, she said.

A Montgomery school spokeswoman said the system of more than 161,000 students does not release data on student suicides.

“Mental health professionals have been telling us all year that the pandemic has had a devastating effect on the mental health and wellness of our young people, even our staff, and we may not know the ripple effects of that for years,” Smondrowski said.

Monifa McKnight, Montgomery’s acting superintendent, welcomed the board’s action. Decisions about regulation changes are made under her administration.

“This actually fits nicely into the work that we’re doing for students and staff in our 2½ -year plan,” she said.

Earlier on Tuesday, the Maryland State Board of Education increased its high school health course requirement to a full year, from a semester, because of a growing number of topics to cover in recent years, including opioid prevention, personal boundaries and consent, sexual abuse and diabetes prevention.

The move came as part of broader revisions to state graduation requirements, which have been studied and discussed over the past three years. Starting with next year’s ninth graders, the number of credits needed for a diploma will rise to 22, from 21, and four math credits are required, up from three.

Under the changes, students also would no longer have to pass tests in algebra, English, science and government to graduate high school. Beginning in 2022-2023, the tests will become end-of-course exams that count for 20  percent of their final course grade.