Beth Yancey and Dennis Padilla say their well wishes to daughter Libby, 10, on the sidewalk outside George Mason Elementary because she didn’t want her parents to walk her up to the school on Tuesday at George Mason Elementary in Alexandria. (Dayna Smith/The Washington Post)

Margaret May Walsh, the newly appointed acting superintendent of Alexandria city schools, welcomed students and parents at George Mason Elementary with a smile and a personal introduction on the first day of school Tuesday.

To many parents and teachers, the longtime Alexandria administrator already was a familiar face.

“You were a principal when my son was in ninth grade,” said Martha Waldron, a retired Alexandria teacher and neighbor who stopped by the school to show the new schools chief her support. “He’s a daddy now. He’s 33. I’m so glad to see you!”

After the School Board’s surprise vote Thursday night to release Morton Sherman from his contract nearly two years early — and just a few days before the first day of school — members appointed Walsh the temporary superintendent, effective immediately.

The board chose an Alexandria veteran with close ties to school leaders and two decades of familiarity with the organization to ease what could be a turbulent transition. At the meeting, they said Walsh’s experience would help her keep things on track.

Incoming kindergartener Jonathan Wyatt, 4, who was, his father said, a little apprehensive about his very first day of school, leans on his father, Jermiane Wyatt, as he waits for the door to open Tuesday at George Mason Elementary in Alexandria. (Dayna Smith/The Washington Post)

“As of five seconds ago, there is no void in the leadership of this school system,” school board vice chairman Justin P. Keating said after the vote.

Walsh is not the only new school leader welcoming back students as schools opened their doors for the year across Northern Virginia: Karen Garza is settling into her new job as the superintendent in Fairfax County, the state’s largest school district. Garza visited classrooms at five schools on opening day, meeting a range of students from jittery kindergartners to high school seniors. Garza said she was “pretty keyed up” for the start of school.

“I hardly got any sleep, I was so excited,” Garza said.

Arriving at Chantilly High School before sunrise, Garza visited students as they gathered for the first day of school and later met seniors in a broadcast journalism class. The teenagers appeared energized, practicing their skills by asking her questions during an impromptu news conference.

Although Garza has outlined a number of improvements she would like to pursue as the new schools chief, when students asked if she intended to make any changes to the school system, Garza replied: “Students largely won’t see any major changes.”

Garza frequently cited the school system’s rapid growth as its biggest challenge — it has a projected enrollment of 184,625, up 3,000 from last year — and said that dwindling federal and state resources have added pressure, noting a possible $150 million deficit next year.

At Clermont Elementary, a school undergoing renovations to accommodate more students, Garza donned a construction hard hat. Behind the school sit more than a dozen mobile classrooms in trailers, and the school added about 70 children over the summer, bringing enrollment to 534.

As a parade of 5-year-olds marched down the halls, Garza counted the students as they passed: The kindergarten class had 27 students. During the economic recovery, class sizes in Fairfax ballooned as the school system cut costs to keep afloat.

“We can do better than that,” Garza said.

In addition to Garza’s arrival as a superintendent in Northern Virginia, Loudoun County is rolling out a national search to replace Edgar B. Hatrick III, who plans to retire in June after nearly two decades at the helm.

And now the Alexandria board is planning a search for both an interim and permanent superintendent.

Sherman, the just-departed Alexandria superintendent, came to the city five years ago from a small district in New Jersey with a mandate to improve school performance. During his tenure, Sherman drew criticism from some educators who questioned the pace of change and the large number of new initiatives.

According to the board, Sherman asked to be released from his contract this summer. It took until Thursday to work out the details of a $281,507 buyout.

Parents and many staff members expressed concern about an abrupt transition so close to the start of school.

Things appeared normal at the school system’s headquarters on N. Beauregard Street as recently as last Wednesday, Walsh said, when she took part in an executive staff meeting that Sherman led. Administrators talked about enrollment projections, staffing and budget priorities for the coming year.

Behind the scenes, Walsh had been approached less than a week earlier about the ongoing negotiations for Sherman’s early retirement and the possibility of her stepping in temporarily.

The District native started her career as an English teacher at a junior high school in Petersburg, Va., in 1975 and went on to jobs in Richmond and then outside Atlanta, where she became an assistant principal at 27. She came to Alexandria two decades ago to open the Minnie Howard Campus of T.C. Williams High School, and she was a principal there for nine years.

In her most recent position, as chief policy and student services officer, Walsh has helped develop the district’s policy platform and has overseen the district’s counselors, social workers, nurses, and psychologists.

Now, as acting chief, Walsh will supervise the city’s 13,500 students in 19 schools and a $215 million operating budget.

She takes charge as the school district struggles to keep pace with growing enrollment and fights a looming state takeover at Jefferson Houston School, which has had chronically low achievement. Also, a middle school task force is considering whether changes made under Sherman’s tenure to divide the city’s two big middle schools into five smaller ones should be retooled or abandoned.

On Tuesday, Walsh crisscrossed the city, hoping to visit as many schools and campuses as she could before the end of the day. (She made it to 17.) She was greeted in many places with hugs from teachers, receptionists, school resource officers, and principals she has worked with over the years.

PreeAnn Johnson, principal of James K. Polk Elementary School, was beaming when Walsh stopped into her office Tuesday morning. She worked with Walsh at Minnie Howard the year it opened and said she screamed with joy when she heard that Walsh would fill in for Sherman.

She called Walsh a “leader of leaders” who had mentored her, along with many other principals and administrators in the school system.

Despite the last-minute change in leadership, Johnson said, “We’re all right.” And pointing to Walsh, she said, “This is why we are all right.”