Three weeks into a partial government shutdown that has stalled nine federal departments, Nargess Lakehal-Ayat spends her days at home, fielding questions from her 12-year-old son that she’s unable to answer.

“When are you going back to work?”

“What are we going to do?”

Then there are the questions the single mother who said she lives paycheck to paycheck can’t answer for herself. How is she going to pay her $2,200 mortgage? Or her $356 condominium fee?

She has borrowed money from her sister to get by. But the last paycheck from her State Department job as a language and culture instructor arrived earlier this month. And she doesn’t know when the next will arrive.

That’s how Lakehal-Ayat found herself Friday, on the shutdown’s 21st day, in a nondescript government building in Falls Church, Va., one of about 200 federal workers who applied to become substitute teachers in the Northern Virginia school district during a hiring event for furloughed workers.

“It’s a very stressful situation. You don’t know when it’s going to stop, when it is going to end,” she said. “And I didn’t want to sit home anymore.”

Fairfax County Public Schools Superintendent Scott Brabrand said Friday’s hiring event was completely booked — just like another one planned for next week. He said he hopes to have federal employees working as substitute teachers by the end of next week.

The job, which requires 60 college credit hours and a high school diploma, pays $14.37 an hour.

“It’s a small gesture of appreciation that Fairfax County Public Schools can share with our displaced federal workers,” Brabrand said. “I am truly overwhelmed at the response. . . . It recognizes the seriousness of families who need a paycheck to survive in the Washington area.”

A surge in substitute teachers would provide a boost to full-time teachers in Fairfax, who sometimes have to cover classes for colleagues who are absent, Brabrand said.

Applicants were fingerprinted and cycled through an orientation that included lessons about managing classrooms, professional expectations and responsibilities.

The event was another sign of strain in the Washington region as the protracted fight over President Trump’s proposed wall along the U.S.-Mexico border thrust the lives of federal workers, government contractors and their families into uncertainty.

Hundreds of federal workers gathered Thursday in downtown Washington, demanding an end to the shutdown. Some have resorted to charities and online fundraisers for food and other basic needs.

School systems in Prince George’s County in suburban Maryland and Falls Church have promised to expedite applications for free and reduced-price meals for students from families affected by the shutdown. Fairfax County said it would not turn away students needing meals.

Arlington Public Schools officials in Virginia emailed families Tuesday, assuring “all families that our teachers, principals and school counselors are available to support students.”

Breana Pegeron, a program analyst for Customs and Border Protection, is up to date on all her bills but said she would start to feel a financial pinch in coming weeks. She has started forgoing daily frills, such as Starbucks, and is seeking work opportunities — including substitute teaching.

She never considered teaching until she came across a post about the Fairfax event. But she taught English as a second language when she attended George Mason University and is keeping an open mind.

“You never know what avenue your life is going to take you,” she said.

This impasse is more nerve-racking than the one Pegeron weathered in 2013 because it has lasted longer.

“What happens if this lasts another 21 days?” she said Friday. “At that point, I’d start to really then be nervous.”