The number of students with Covid-19 has risen since schools began their second semester a month ago, prompting the government to call on them to respond appropriately.
Government spokesman Thanakorn Wangboonkongchana said Prime Minister Prayut Chan-o-cha ordered the Education Ministry to oversee Covid-19 measures in response to the rise in cases.
Gen Prayut was concerned about both the health of students and the possible spread of the virus to their family members, the spokesman said.
Mr Thanakorn said about 50% of infected students did not have symptoms.
Schools have been asked to disinfect their premises, he said. Parents should also regularly use antigen test kits to check if their children are infected before sending them to school, he added.
Kesthip Supawanich, an Education Ministry spokeswoman and deputy secretary-general of the Office of Basic Education Commission (Obec), said Obec has instructed schools to implement action plans to deal with the rise in cases.
If a case is detected in a classroom, schools can allow students with mild symptoms to learn through other channels, including online platforms, Ms Kesthip said. Students who are close to infected students or at-risk groups can continue their studies at schools and follow health measures, she said.
The office wants schools to continue on-site classes to ensure their quality of education while the government speeds up vaccinating students, she said.