Calling for an end to wage discrimination, an alliance of non-permanent workers at elementary and secondary schools began a three-day strike nationwide on Wednesday.
More than 50-thousand workers reportedly participated in the walkout,including cafeteria cooks, dietitians and administrative assistants for teachers.
The workers have been calling for a basic pay increase of about six percent,or some 80 percent of the salary earned by the government's lowest-ranking civil servants.
However, authorities have drawn the line at a wage increase of 1.8 percent.
The three-day walkout could get longer if they fail to reach an agreement.
Nearly 44 percent of schools across the country, or 4,601 schools were not able to provide lunch for their students.
The majority of affected schools provided substitute food, including bread and milk to students, while some students had to bring lunch from home.
"I had difficulties going to work this morning. I had to prepare lunch for my kids. I hope the situation gets back to normal soon so that children can get proper meals as usual."
Other schools, mostly middle and high schools, have not arranged alternative options, as most schools finish early this week due to final examinations.
As for after-school daycare services, teachers and regular school employees were mobilized to cover for the workers participating in the walkout.
On the same day, tens of thousands of non-regular workers in the public sector held a rally in Seoul, demanding an end to discrimination and urging the government to reclassify them as regular workers, as promised.
Yoon Jung-min, Arirang News.