It's all part of the Fridays for Future schools strikes for climate leading up to activist Greta Thunberg's rally at the United Nations headquarters in NY on Monday, and a global general strike on September 27.
Children in Australia help kick off a historic global day of action seeing young people demand adults move faster to tackle climate change.
The movement is partly inspired by Swedish teenager Greta Thunberg, who has staged weekly demonstrations over the past year under the hashtag #FridaysForFuture, calling on world leaders to step up efforts against climate change.
Friday's protest is part of a larger movement, Fridays for Future, which encourages young people to demand real change from their lawmakers.
"As we deal with devastating climate breakdown and hurtle towards unsafe tipping points, young people are calling on millions of us across the planet to disrupt business as usual by joining the global climate strikes", according to a statement on the organizers' website.
"We're here to send a message to people in power -- the politicians, showing them that we care and this is really important to us", said 16-year-old Will Connor.
Geoff Barton, general secretary of the Association of School and College Leaders, said: "It is great that young people want to highlight the climate crisis, but we have consistently said that pupils should not miss school to take part in protests and should instead talk to their teachers about activities which can take place in school".
More than 30 heads of state and government have signed an appeal for greater action to fight climate change circulated by Austrian president Alexander Van der Bellen ahead of next week's conference on global warming at the United Nations in NY.
"Though many of us might have passed on before our species extinction occurs, the ones who will endure the brunt of the destruction are the youth, the Indigenous and the poor", said Andrea Shaw, a New York City-based organizer for Earth Strike.
"And we have to stand up and fight", her friend finished for her.
Signs at a Global Climate Strike march in Washington D.C. on Sept. 20 2019. Brendan Smialowski AFP
"But just at the time when we need to ramp up climate solutions, we have elected a government that wants to open the floodgates to new coal, oil and gas projects that put all of us at risk".
"I think it is just a disruption".
Australia's conservative government - while stopping short of outright climate change denial - has sought to frame the debate as a choice between jobs or abstract Carbon dioxide targets.
"Climate change is an existential threat-and we are already facing the effects".
One said: "We used to call it "mitching off" in my day. now it's called a climate change protest".
"The facts are, there is no link between climate change and drought, polar bears are increasing in number", he said.
NSW Education Minister Sarah Mitchell tells Alan she does not support the strike.
Labour leader Jeremy Corbyn, who will be addressing a rally of climate strikers outside Parliament on Friday, has taken to Twitter to back the children going on strike, saying they "are leading the way and I'll be proud to join them tomorrow".
The protests come ahead of a climate summit at the United Nations next week convened by secretary-general Antonio Guterres to urge countries to up their climate efforts.
He said his department is holding hearings across the state, and working on reviewing the impact of climate change, giving an example of changes he's found in the Pennsylvania Department of Transportation's budget.