Analysts said earnings from Chinese online education companies are competitive in terms of time and energy spent, especially when you factor in the fact that some of the US public school teachers are often underpaid and struggle to make a decent living.

Catherina, 46, a former public school teacher from Kentucky in the US, now works part-time with VIPKid. With an average of five classes per day, each of which lasts 25 minutes, she earns roughly $24,000 to $36,000 per year.

The more she teaches, the more she will earn-bonus could mean teaching on holidays.

Executives of the Beijing-based company said a foreign teacher could earn more than $70,000 a year, rivalling the average annual income of a public school teacher in the US.