A few students were seen wearing casual attire for the start of the new school term on Tuesday morning, in response to protesters' calls for freedom of dressing, but most arrived in their usual uniforms.
Some parents had been warned students would be sent home if they were not in uniform, despite official approval to dress casually for the first day back at school.
The suggestion they leave their uniforms at home for the first day of the school term was made by the Bad Students group, which predicted that students at 23 schools would participate.
Two well-known schools, Samsenwittayalai and Triam Udom Suksa, were among them, but most students arrived in their uniforms on Tuesday morning.
Teachers welcomed students as usual at the gates and those who chose to wear casual clothing were not barred from entering.
Students who were out of uniform said it was their body and they had the right to decide the way they dressed it. They expected the Education Ministry would consider their message.
Prime Minister Prayut Chan-o-cha said while meeting students displaying education projects at Government House on Tuesday that school uniforms allowed officials to easily recognise students in the event of any dangerous incidents in public places.
He also said school uniforms helped save on clothing costs. Students would need many different garments if the school dress code were lifted.
In Nakhon Ratchasima province, all students at Suranari Witthaya girls school were in their uniforms. It was among the 23 targeted schools.
School director Wilas Duang-ngern said parents were told in advance that their children should comply with the dress code of the Education Ministry, and any students who showed up in casual attire would be sent home to change into their uniforms.
In Khon Kaen province, about 50 students at Kaennakhonwitthayalai School wore casual attire. The school director called them to a closed-door meeting.
Noppadol Singkheeree, a deputy director of the school, said it was inappropriate for students to wear casual attire to classrooms. The Education Ministry did not allow it.
The school management would not consider students' request for casual attire as long as the ministry adhered with its school uniform regulation, he said.
A girl at the school said wearing casual clothing would help protect girls from people taking upskirt photos.
The Office of the Basic Education Commission (Obec) had earlier given its approval for students to wear casual clothing for one day.
Secretary-general Amporn Pinasa said on Monday students should be allowed to don casual attire for the first day of the new term, because going to school to study was the best thing that could happen to society.
However, it was a one-day concession. School dress codes would still apply, he said.
- Photos: Students in casual attire