Social media on Monday reported photos of students from different schools showing the three-fingered salute from the Hunger Games films, a form of silent resistance to the Prayut Chan-o-cha government.
Students in many schools on Monday flashed the three-fingered salute during their morning assembly in front of flag poles and used white ribbons as a gesture against dictatorship.
Photos and videos of students showing the three-fingered salute and white ribbons circulated online with the use of a hashtag against dictatorship.
There were reports that many of the students had been punished by their teachers. Some of the teachers reportedly slapped students' faces and mobile phones onto the ground to prevent from recording videos.
Some pages reported that a student whose phone was slapped out of his hand later posted an image of the teacher apologising with a wai gesture in Nakhon Sawan province.
At some schools, teachers announced in front of the flag pole that the schools prohibited the three-fingered gesture.
At Srikranuanwittayakom School in Kranuan district of Khon Kaen, a student said police officers travelled to the school and seized white ribbons after they were given to students Monday morning.
Chatchawan Apirakmankong, a former MP candidate for Khon Kaen from the disbanded Future Forward Party, voiced his disagreement with the police officers' visit to the school and taking away the white ribbons.
He called on the authorities to stop harassing students.
A tweet depicting a teacher tying a white ribbon around a student's neck was retweeted more than 20,000 times on Monday.
Education Minister Nathapol Teepsuwan gave an interview to the press on the three-fingered salute and the anti-dictatorship hashtag, saying he understood students' right of expression and accepted different opinions.