"It was a bit of funny to see my teacher through the camera, though. He obviously goes faster in teaching when it comes to video teaching," said Lu Zihang, a 17-year-old student at the school.

"Maybe it's because he couldn't get a full impression of our reactions. I hope the teacher will slow down a bit if we learn new lessons this way."

Vice-Principal Qiu said teachers cannot have full control of their class during the long-distance classes. In a class of 40 students, the teacher can only see three of them at the same time on the screen.

"This is more like a kind of service that the school provides to the students," Qiu said. "We give students a platform for them to keep learning at home, but at the moment, we do not force them to take the classes. If some students prefer to take a rest on smoggy days, it's fine."

On Dec 5, Nanjing, capital of Jiangsu province, was hit by heavy smoggy weather, with authorities declaring the highest level of air pollution. All primary and middles schools were forced to suspend classes for four days, according to the city's education department.

Though no Level 1 air pollution warnings were been issued in Beijing during 2013, Qiu said the system could be put to use in a range of different circumstances that prevent students from traveling to school.

Chu Zhaohui, a senior researcher at the National Institute of Education, said that the idea of online classes with video links is a good one, but not very applicable on a large scale.

"Beijing Jingshan School has a long history and very good reputation in basic education, and most students started to use computers at a young age," he said. "But this is not the case for every school. Not every student owns a computer at home, and computer skill varies largely among students."

He also says the system may cause more problems for elementary students in first and second grades because staring at a computer screen continually for 40 minutes may harm their eyesight.

Zhang Min, a 39-year-old mother in Beijing, said that she would prefer her 12-year-old daughter take a rest on smoggy days.

"I don't think this way of teaching and learning can be as efficient as a real classroom because the teachers can't really get a good grasp of students reactions," she said. "Plus, heavily polluted days don't last long. I would prefer my daughter to take a break for two or three days if the terrible weather really arrives."