Amid a sharp decline in the school-age population due to a rapidly dropping birth rate, 1 out of 6 elementary schools in Seoul will have fewer than 40 students per grade level, government research suggested Thursday.

The number of "small-scale schools" that have fewer than 240 students will increase by 101 in 2028, an almost 50 percent increase from this year with 69 schools, according to the Seoul Metropolitan Office of Education's prediction on arrangements of schools from 2024 to 2028. This means 16.5 percent of elementary schools in the capital city will lack students in just four years.

Though small schools do not directly imply the imminent closure of schools, the schools could face difficulties in operation, as fewer than 240 students per school means there could only be two classes per grade.

With only two classes in one grade, it would be a formidable task for schools to operate after-school programs or plan activities such as a sports day or field trip. Schools could also face financial challenges in meeting the costs of school lunches due to a lack of students.

Teachers could bear the burdens of the workload, as the amount of administrative work stays the same while the number of teachers decreases due to a drop in the number of students.

As of this year, the average number of students per elementary school is 608. That number is expected to decline to 578 in 2025, 555 in 2026, 526 in 2027 and 496 in 2028, when the number of students per school is projected to fall below 500 for the first time.

The decline is also apparent in the number of schools already closing due to a lack of students.

Twenty-seven schools in 17 cities and provinces across the country face a shutdown this year, the highest figure in five years. This is about 40 percent more than the number of schools that closed last year.

North Jeolla Province is expected to see seven schools close this year, the most for any region, followed by six in North Gyeongsang Province and five in South Jeolla Province.

"The school-age population is shrinking due to the declining birth rate, and the number of children applying to elementary schools is also sharply declining," an official said. "Even in small schools, we are working to appropriately organize the number of classes and students per class."