Andy Yung, a prekindergarten teacher in New York City, is adept at raising money online for ambitious classroom projects, but even he sometimes pays for supplies out of pocket.

And he has company. According to a U.S. Department of Education survey released Tuesday, 94 percent of public school teachers in the United States reported paying for supplies without reimbursement in the school year that straddled 2014 and 2015.

It made little difference whether they taught in cities, suburbs or rural areas, or whether or not their students were poor — virtually every public schoolteacher said they had used their own money for their classrooms.

“It’s almost expected, especially in the summer months creeping up into September,” Yung said. “It’s just something we kind of naturally do.”

The teachers who reported spending their own money on supplies shelled out $479 each on average, according to the survey. Seven percent reported spending more than $1,000.

The findings, based on a nationally representative sample of tens of thousands of teachers, underscore the demands teachers across the country have been making in recent months amid protests over stagnant pay and underfunding.

The latest took place today in North Carolina, where some schools canceled classes as throngs of teachers and others marched in the capital. Similar rallies have been held this year in Arizona, Kentucky, Oklahoma and West Virginia.

The protesters have been successful at extracting concessions from conservative lawmakers, though the deals have not always fully met their demands.

On average, public schoolteachers earned just under $60,000 last school year, according to the National Education Association, but pay is so low in some areas that officials have been recruiting overseas.

Limited budgets and red tape have led some teachers to seek outside funds for classroom projects. Like Yung, some use DonorsChoose.org, a crowdfunding website where educators can solicit donations for supplies, trips, and other projects.

In March, he raised almost $3,000 for materials to teach his students about insects. The project was a hit, but the children wanted to see live bugs, too.

The cost of the additional materials was less than the DonorsChoose.org $100 minimum and Yung had already reached a city reimbursement limit, so he spent his own money to buy two more books, an ant farm and caterpillars.

“I don’t want to deprive my kids of this awesome experience of witnessing a caterpillar turn into a butterfly and watching ants burrow because it’s such an interest that they have right now,” he said. “So I went on Amazon.”