The sight of students puzzled Karen Joseph.

They appeared on the weekend or after school, at outdoor cleanups and other community service events hosted by the Herndon Middle School PTA.

School staff members explained to Joseph: Students showed up because they were hungry.

At the events, the children could fill up on complimentary pizza and sandwiches.

“I was blown away. I live in Northern Virginia. I live in Fairfax County. You’ve got to be kidding me,” the former PTA president remembered thinking. “These are kids that my kids were in school with.”

The experience resonated with Joseph, leading to an aspiration — she wanted to help end childhood hunger in Herndon. She formed Food for Neighbors, an organization that for nearly two years has collected bags stuffed with donated canned and other nonperishable goods from the stoops and front porches of Northern Virginia residents.

The process is unfussy — residents request a red bag online and fill it with items appearing on a grocery list provided by the organization. Volunteers retrieve the donations on collection days.

The haul from a recent Saturday yielded more than 6,100 pounds of food from hundreds of donors, Joseph said.

More than two dozen drivers navigated routes mapped by Joseph, collecting donations from hundreds of families.

They transported the food to Herndon and Irving Middle Schools, where other volunteers sorted through mounds of granola bars, canned pasta and instant macaroni and cheese that would be divided among eight Fairfax and two Loudoun County schools.

At Herndon Middle and Herndon High School, the food is stowed in food pantries students use to help sustain them during weekends, holidays or when money from a family’s paycheck dwindles.

On weekdays, students can depend on breakfast and lunch from school cafeterias. But for some, finding food outside school hours proves challenging.

The donated goods are one option for students who may struggle with hunger in Fairfax, Virginia’s largest school system. Several schools have established pantries. More than two dozen schools offer students free snacks after school. The district will, for the third year, provide meals to students over the summer at community barbecues.

About 29 percent of Fairfax County students are eligible for free or reduced-price lunch, according to Virginia Department of Education data.

At Herndon Middle, counselors store bins of food in their offices for hungry students who may visit, said social worker Pat Humphrey. The school’s food pantry is opened to families before extended breaks from school.

“There is a sort of misconception when it comes to Fairfax County because we do have a reputation for being one of the wealthiest counties in the country,” Humphrey said. “It’s kind of difficult to know which schools are . . . needy. But it exists.”

Some students live on their own, covering rent and other expenses. Others belong to families struggling to make ends meet, said Dianna Sosa, a social worker at Herndon High School.

The consequences of hunger manifest in classrooms — unfocused and angry, students act out and are unable to concentrate, Sosa said.

One Saturday, Tiffany Nguyen, 17, unpacked granola bars inside Herndon Middle School. She was one of dozens of students who devoted their Saturday morning to the cause.

The Herndon High senior has volunteered with Food for Neighbors since shortly after it began, augmenting the organization’s work by spearheading an effort that provides students with fresh bread.

Nguyen has seen the donations help her friends. The level of need frustrates her.

“It’s tragic, honestly,” Nguyen said. “If we live in a country that’s considered one of the best and one of the most developed . . . it’s not okay for this level of hunger to be existing in this community.”