Schools around the world have closed their doors because of the coronavirus pandemic, leaving more than 1.5 billion children stuck at home. While it's a great inconvenience for many, it has created a spike in demand for online learning.

Educational institutions are introducing online courses and some education technology startups are temporarily offering free classes to help offset the impact of school closures.

Take Byju's, an India-based education startup named after its founder, Byju Raveendran. In early March, it announced it would give children free access to its learning app, which it says had more than 40 million users at the end of last year. Around 3 million of those paid between $150 and $200 for an annual subscription.

Since the announcement, the company says it has experienced a 60% surge in students using its products, which range from interactive video lessons and live classes, to quizzes and exam preparation.

A nationwide lockdown, ordered by Prime Minister Narendra Modi in late March, means that India's school-age population of around 300 million is suddenly having to home educate.

"The outbreak is clearly increasing the appreciation of online education," Raveendran tells CNN Business. "This could be a turning point for the industry, ushering in an increased usage of this format and changing habits in terms of how kids learn and how teachers teach," he adds.