On a weekend evening in Nanchang, Jiangxi province, Liu Yawen, 12, clicked an app on her iPad, greeted her teacher in the United States, and started her one-to-one online English lessons at home.

Having two or three lessons a week - each lasting about 25 minutes – is how the sixth-grade primary school student had been studying for more than a year.

"Talking to teachers from English-speaking countries has really helped me to overcome the nervousness to speak in another language in public," Liu said.

She has since competed in an English speech contest and won the prize of a study tour to the US.

Shi Xia, 47, in Lanzhou, Gansu province, has also been taking online English courses for more than two years.

Shi, who struggles to use English to communicate with business partners abroad, enrolled in the online course because it is difficult to have the opportunity to talk to native speakers in Lanzhou.

"The course has really boosted my confidence in talking with foreigners, so when the opportunity presented itself recently, I didn't hesitate to come to the US for a master degree," she said.

Online teaching, especially English lessons taught by teachers who are native speakers of the language, is becoming increasingly popular in China.

A report released by iResearch consulting company in August 2017 showed that the market size for children's online English education in China would surpass 5 billion yuan ($338 million) in 2019, with the number of users reaching 8 million people that year. Some companies have already benefited from the growing need and are developing and expanding quickly.

iTutorGroup, established more than 20 years ago, is a leading player in online English education. The platform has already signed up 20,000 teachers around the world to conduct one-to-one or one-to-few English teaching by video to more than 200,000 paid users in China.

Eric Yang, founder and CEO of iTutorGroup, said online education will experience explosive growth in the next three years, and eventually become the mainstream education method.

Online English education is convenient and time-saving, and more importantly, it can increase the student's interest in the language and achieve good learning results, he said.

By combining information technology and artificial intelligence, every student can have different teaching curriculums and teaching materials based on their characteristics, Yang said.

However, not every native speaker is a good English teacher, and a key for healthy development of the sector is to ensure that every teacher on the platform has teaching credentials, he added.