Primary students in Hanoi and Ho Chi Minh City need to be on their best behaviour in class. There's no space to turn around, let alone cause mischief.
A teacher from Le Van Sy Primary School in HCMC was panicked after receiving her class last month. "Sir! My class has 57 pupils. Is this a mistake?" she asked the school principle.
Most classes in primary schools in the cities have nearly twice the number of students allowed by the national standard 35 to a class.
"Just imagine 45 children pushing each other the whole day in a class with only one teacher and an assistant. It's a scary thought," said Ngoc, whose child attends Bau Sen Primary School in HCMC.
But there is nothing she can do.
Some teachers have said large class numbers lead to health problems and that the children's eyesight suffers. Three children share a desk designed for two while everything is shifted forward to make more room, they said.
Ta Tan, head of the education department in Tan Phu District, admitted that only one school in the district meets the standard for class numbers. Other schools have 47 students to a class while 60 children cram into a classroom at Le Lai School.
A former head of an education department in HCMC who didn't want to be named, said the parents' false views and beliefs were partly to blame for large classes at several schools.
"Just over ten years ago, the city experimented with English classes at a couple of schools. They were successful and words got around. Parents wanted their children to study at those schools, even if the facilities weren't all that good," he said.
In Hanoi, many parents favor Kim Lien Primary School in Dong Da District. Children end up in a classroom with around 65 others.
The school principle said around 50 percent of children at the school live in a different district. There are rules in place that say children must attend primary schools in the district they live in.
Amplifiers have been used by teachers at the school to deliver lessons for several years.
A teacher at the school said her voice was hoarse after teaching the children for a day without a microphone. "I couldn't even muster up the energy to talk to my husband and child afterwards."
Nam Thanh Cong School in Dong Da District is also a popular school. Children living within the district account for 600 students when the school is only meant to cater for 500, school officials said.
A mother in Hanoi said, "No matter how good or enthusiastic a teacher is, they cannot effectively teach such a big class."
An education official in Da Nang, a city that has also started to see overflowing primary school classes, agreed, "The teacher cannot monitor each student."
Bui Thi Kim Dung, a first grade teacher at Nguyen Van Troi Primary School, HCMC, said it takes more time to teach the students to write and sit properly for example, than to keep them from running around.
Another first grade teacher from a different school in the city, who wished to remain anonymous, shares the same opinion. "My class has 50 students. I never get a moment's rest. I have to go around and make sure that every student is writing the right line and sitting properly."
Tan, the education official from HCMC's Tan Phu District, said he used to think that only some years would yield large classes. He thought more parents would have children in certain years according to the Chinese zodiac.
"But that's not true. The student population has increased every year due to the number of migrants from the Mekong Delta, and northern and central regions. The responsibility of schools is to receive all the children in their area.
"The only way to solve this problem is to build more schools," he said.