Tens of thousands of students have taken to the streets nationwide to air their frustrations at the lack of government action to tackle climate change.
Rallies were held on Friday with students encouraged to use a "climate doctor's certificate" and take a sick day from school citing global-warming concerns.
Several thousand people descended on Melbourne's Flagstaff Gardens before marching through the city centre.
Liam Cranley said he took his children Dario, eight, and Olive, 11, out of school to attend the March because they asked him if they could go.
Mr Cranley said their school had no qualms about his children missing class and he believed it was important to take a stand as governments at all levels needed to accelerate action on climate change.
"We're not going to be able to live here much longer if the heat keeps going up," daughter Olive told AAP.
A group of students from Melbourne Girls' College attended after hearing about the rally from a teacher.
"I believe it's worth missing half a day of school just to make sure that the next generation will actually get to live and have an education here on our planet," year 7 student Erin said.
Groups of protesters in Melbourne blocked traffic as they staged sit-ins at several major intersections, holding up trams and vehicles before ending up at Victorian Labor headquarters in Docklands.
Meanwhile, hundreds of people converged in Sydney outside the office of Environment Minister Tanya Plibersek to chants of "shame" and "shift the power".
As Australia prepares for another summer of extreme heat and bushfires, the students said they were extremely disappointed with the Albanese government for not doing more since gaining power.
"I was expecting at the very minimum, no new coal and gas - that's a very minimal demand, that we shouldn't make it worse," 16-year-old Alexander Duggan said.
"Governments want to pretend they're doing things, but things like the offset scheme are just to make us think that they're doing things - it doesn't address the root causes."
School Strike 4 Climate organiser Nirvana Talukder said students have been fighting for the same demands since the first rallies in 2019.
"We want a government that cares for the lives of its people and the planet, not a government that funds a crisis that kills," she told the crowd in Sydney.
Anjali Beames, 17, has been striking from school all week, studying on the steps of Parliament House in Adelaide alongside other students from the South Australian Youth Climate Alliance.
"I am studying for my future, but I am worried that without real action on climate change my future will be bleak," she said.
Many of the marches were heavily entwined with First Nations concerns.
Torres Strait Islander law student Chelsea Aniba travelled from Saibai to Melbourne, where she joined the student protest to explain how her people were on the front line of climate change.
"It's affecting our homes, our gardens, we can't really grow our traditional foods like we used to anymore," she said.
"Even our seasons are being changed.
"And of course, the main one, which is the sea levels are rising."
Torres Strait Islander elders Pabai Pabai and Paul Kabai are in Melbourne for hearings in the landmark court case they brought against the Australian government for climate inaction and spoke at the strike.
Mr Pabai said he was happy to be supporting the school strike to help deliver a message to the government.
"I say to them, 'help us'," he said.
"I say to them, 'the time for politics must stop, you must take action urgently to protect us from climate change, if you don't, we'll lose everything'."
