Schools should not add an unnecessary academic burden on primary and secondary students through online classes, the Ministry of Education said on Tuesday night, amid criticism that online teaching has significantly increased the workload of students and teachers.

Answering the ministry's call in late January, education authorities, schools and after-school training institutions have been offering students online courses during winter vacation as the spring semester for schools has been postponed due to the novel coronavirus outbreak.

An official with the ministry said no online classes should be provided to kindergarten students, and primary students in lower grades can choose whether to take the classes or not.

For students in higher grades, the schools should limit the time and amount of online learning and should not spend too much time on it, the official said.

Online courses should be related to infection prevention, psychological health and educational activities and content, rather than subjects that put extra pressure on students, the ministry said.

Schools should make good use of existing online teaching materials, rather than putting extra workload on teachers and asking them to record online classes.

Online after-school training institutions that provide classes ahead of the teaching schedule, offer exam-oriented training or promote learning anxiety among students and parents will be dealt with seriously.