The 12 digital lessons will be available to download until the end of June.

They include tours of the International Space Station and the inside of a human eye, which "can be played on your own, or with parents or friends".

The worlds offer creative writing and puzzles as well as build challenges.

Other lessons include:

• puzzle games to teach students how to code and think like programmers

• a tour of Washington DC's most historic sites, including the White House, the Pentagon and the Lincoln Memorial

• a game about generating power from alternative energy sources, such as wind and nuclear

"Educators around the world are doing everything they can to provide digital lessons for the half a billion students who are out of school due to the Covid-19 pandemic, Minecraft owner Microsoft said in a blog.

"This is not an easy task and we want to do our part to help keep young minds sharp and stimulated."

Many educational resources previously available for schools to buy only are now free for a limited period to allow parents access to lessons.

Meanwhile, website Hegarty Maths, which remains a subscription-only service, has seen unprecedented demand as pupils log on in huge numbers.

On its website, it told visitors: "We are doing everything we can to ensure the site stays stable and are adding more servers."