His two sons were graduating from elementary and middle school, but Kareem Starks couldn’t afford gifts.

“I bought a bunch of balloons,” he said. The rest of his money went to food and rent.

Starks earns $7.25 an hour as a McDonald’s “food handler” in Greenpoint. He is one of 57,000 workers across New York City trying to live on the meager wages paid by the fast-food chains.

He is also among thousands of fast-food workers across the country who have launched a new movement — the first of its kind in the fast food industry — to raise their pay and organize into unions.

The historic campaign has included one-day strikes and rallies here and in about 60 other cities, with the workers demanding a doubling in pay to $15 an hour and the right to organize unions in their workplaces without fear of employer retaliation.

Wages have always been low in fast food. The difference now is that these are no longer jobs held mainly by teenagers. Increasingly, as middle-class jobs have disappeared, more parents and other adults have taken and kept fast-food jobs as the only work they can get.

Starks sought work at McDonald’s after getting laid off from his job as an assistant gardener at the city parks department, where he had worked for five years. Today he has a second job at the Battery Park City Parks Conservancy. Still, he said, it’s tough to make ends meet.

UFT President Michael Mulgrew said improving the lot of fast-food workers and other workers earning minimum wage is crucial to improving the educational outcomes of their children.

“Many fast-food workers are parents of children we teach every day,” he said. “When parents get miniscule wages, it has a huge impact on their children. The constant financial stress of not earning enough to pay their bills takes a toll on families and children.”

Besides the impact of low-wage jobs on children and school communities, there is another way that the plight of fast-food workers affects New Yorkers: Taxpayers fund the public assistance programs on which fast-food workers depend for survival.

Fifty-two percent of the country’s fast-food workers — who on average make just $8.69 an hour — apply for one or more forms of public assistance such as food stamps, according to a new report by the University of California at Berkeley Labor Center. The cost to U.S. taxpayers is $7 billion a year.

In New York, where 60 percent of the state’s 104,000 fast-food workers receive some form of public assistance, the bill for taxpayers is an astonishing $708 million, second only to California’s.

“McDonald’s and the other fast-food companies are passing along the costs of their low wages and lack of benefits to taxpayers,” said Jonathan Westin, the executive director of New York Communities for Change, who is spearheading the campaign to organize fast-food workers in the city. “We’re subsidizing their exploitation of workers, and it has to stop.”

McDonald’s, whose low wages and paltry benefits to workers cost taxpayers $1.2 billion in public assistance, instructs employees to apply for public assistance via its “McResource” employee helpline.

McDonald’s worker Nancy Salgado taped her phone call to the McResource line. “I can give you a number that will be helpful. You can ask about things like food pantries,” she was told. She was also told how to apply for food stamps and Medicaid.

Starks, who has also had to apply for food stamps, said he joined the fast-food workers movement to give his boys a better life. The beginning of the school year is especially difficult, he said.

“If I didn’t have a second job, how would I buy school clothes for my kids and pay rent?” he asked.