With schools in China remaining closed due to the novel coronavirus outbreak, the Ministry of Education has launched a national online learning platform and started broadcasting classes on television to help the country's 180 million primary and secondary students keep learning.

A national cloud learning platform launched on Monday has provided materials for students in middle school and high school, according to a statement issued by the ministry.

The e-learning platform is meant to provide resources for students but does not replace classroom learning, the ministry said.

At the same time, classes for primary school students have started airing on China Education Television Channel 4.

The division of learning platforms for different levels of students is to limit the time primary school students spend online and protect the students' eyesight, as well as prevent network congestion from too many students going online at the same time, the ministry said.

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 since the spring semester for schools has been postponed due to the outbreak.

However, online teaching has its weaknesses compared to face-to-face learning and has encountered some criticism from students.

Alibaba Group's communication app DingTalk has begged students to stop venting anger on the software after they gave it poor grades when it is used to attend online classes.

The students, who were hoping for an extended winter holiday, were not happy when DingTalk, originally designed for China's white-collar workers, adapted to the outbreak by offering the service to help primary and middle school students take online courses.

After the app launched new features such as homework grading, the ability to livestream classes and watch video replays, it received many one-star reviews from not-so-enthusiastic students.

On Tuesday, DingTalk had a score of 2.6 out of 5 stars, despite being No 1 in the business category.

Many of the roughly 940,000 reviews on the app on the Apple store platform criticized DingTalk for spoiling their plans for a rest during the winter vacation.

"My holidays! I love DingTalk, here is one star for you," said one review.

In a cartoon music video posted on its Sina Weibo late on Sunday, DingTalk begged for mercy from the "young heroes" and said the app cannot withstand so many bad reviews.

"I know, young heroes, you were not expecting such a fulfilling holiday, it's difficult for you," the video said. "It's also difficult for us to make a living. I am only 5 years old yet I have started to lose hair due to overworking."

Yin Ting, a high school teacher in Shenzhen, Guangdong province, said her school has offered online classes for more than 10 days, and she is not a fan of the new teaching method.

Not all students have strong self-discipline, and when teachers are not around, it's easy for them to stop paying attention to the class, so the online classes are not efficient, she said.

"I can see students taking notes and give them immediate feedback when I am teaching face to face at school, but I can't do this during online courses," she said, who added that there is almost zero engagement between teachers and students online.

Liu Yanming, a sixth-grade primary school student, agreed.

"I tend to focus more on classes when my teachers and classmates are around me. For the online classes, it's easy for me to lose concentration," he said.

Conversely, Li Xiao, a fifth-grade student at Beijing Chaoyang Experimental Primary School, said it is convenient to take the online classes.

"I can listen to the difficult part several times, and press pause any time I want to take notes," she said.