Schoolchildren all over the world have been taking part in a school strikes once again as part of a global day of climate action.
The organisation Fridays for Future called for the strikes to restart as part of the day of action.
Fridays for Future was behind the school strikes which started last year, but they ended once schools closed because of the coronavirus pandemic.
However, with many children now back in the classroom, it has restarted the strikes to highlight the threat of climate change.
Because the coronavirus pandemic is still with us, marches can't take place so this year there are digital marches that people can take part in instead.
Fridays for Future is asking people to post photos on social media, use hashtags and register strikes and share the live stream link as well as protest online.
Climate activists have had to find new ways to protest and use digital activism to demand climate change because of the coronavirus pandemic.
The rules around gatherings in the UK are much more complicated than with the 2019 school strikes, because of coronavirus and measures like the 'rule of six'.
Protests have to be properly organised and strict social distancing has to be followed otherwise the gathering is illegal.
There are legal restrictions in England, Wales, Scotland and Northern Ireland about the numbers of people who can meet up outside.
Fridays for Future said the coming months and years are really important to keep the global average temperature rise below 1.5 degrees. By keeping to this target it could reduce the risk of causing irreversible damage.
It is vital that the climate crisis doesn't get forgotten in the shadow of the coronavirus but is regarded as the utmost priority. Fridays For Future will keep protesting as long as exploitation of nature is allowed to continue.
School strikes mean children could miss a day of school. The Department for Education said: "We share the passion young people have for tackling climate change and we want them to be engaged with such an important issue but we do not condone pupils missing out on education as a consequence."
Climate campaigner Greta Thunberg announced earlier this week on her social media that the strikes would be restarting. Greta said the strikes would be held "in over 2500 places around the world and counting!"
She also shared a map showing all of the different locations where events would be taking place.
Meanwhile, a song has been released which is being described as a new anthem for young people wanting the government to take action against climate change.
The song was co-written by Bafta-winning songwriter Ellie Wyatt, who writes for CBeebies programme Tee and Mo.
The song was made with young climate strikers from around the world, including Fridays for Future.
Lauren, aged 16, who is in the music video said: "Climate action is something I've been doing since I was seven, and yet, at sixteen I'm still out on the streets begging for change. I joined the youth climate strikes in Brighton from the start, but made it clear to my school that, like Greta Thunberg, I would continue working hard at achieving good grades, even if I was striking."
Prime Minister Boris Johnson gave a speech to the United Nations Climate Action Roundtable on Thursday 24 September and asked world leaders to make commitments to cut the amount of greenhouse gases being released into the atmosphere.
He said we should "look ahead to how we will rebuild, and how we can seize the opportunity to build back better.
"Let us be the leaders who secure the very health of the planet for our children, grandchildren and generations to come."
Have you been taking part in the strikes online? Let us know in the comments below.