By ALFREDO ALVARADO

Union activists added another 8,000 post cards for Mayor Bill de Blasio to receive during the holiday season.

But instead of a Christmas greeting, their message called for free universal lunch for all of the city’s public school students.

Executive Vice President Donald Nesbit of Local 372, which represents cafeteria workers, delivered more than a dozen bags of post cards to City Hall on Dec. 15. The post cards were signed by people who want to see public schools offer free lunch to all students regardless of their ability to pay.

The mayor supported universal free lunch during his campaign; now activists want him to offer free lunch as he promised.

Nesbit was joined by City Council members Mathieu Eugene and Margaret Chin and activists from Lunch 4 Learning, a coalition that has been working with DC 37 and many other groups, to make free and healthy meals available.

Only 38 percent of high school students eat school lunches, partly due to the stigma of poverty, according to Lunch 4 Learning activists.

Pamela Stewart-Martinez, co-president of the Citywide Council on Special Education, said 250,000 of the 780,000 students who are eligible for free or reduced-price meals do not participate. Some don’t participate because their parents earn more than the federal poverty rate and earn too little to pay for lunch.

Students have to fill out forms and verify their income to be eligible for a free lunch. But some students prefer not to eat lunch at all because that would identify them as a low-income student. Nesbit and Lunch 4 Learning would like Mayor de Blasio to do away with the paper work all together and make lunch available to all students.

“We’ll kept coming back to City Hall until all students can eat for free,” explained Nesbit, who worked in school cafeterias for a dozen years.

Earlier this year, Lunch 4 Learning announced that 30,000 signatures were gathered for the free lunch on-line petition on Change.org.