A crowd of about 200 students and supporters gathered in the Hub forecourt in Springwood on Friday morning as part of the School Strike 4 Climate action happening around Australia and internationally.
"The biggest issue in modern history is going to be climate change," Winmalee High student Adisen Wright told the crowd.
"Here in Australia we are so backwards with our government and we are so backwards with coal. This is about bringing awareness to renewables.
"I don't care if I get expelled for standing here today … you have to take action."
Other students spoke of their concerns for the future and their children's future.
"Our planet is more important than our education sometimes and we have to take a stand," said 11-year-old Olivia Mountain from Faulconbridge.
Sisters Madeleine, 10, and Josephine, 8, Ptolemy and their friend Emiliana Hart, 9, from Winmalee decided to organise the gathering in Springwood to raise awareness about climate change inaction.
"Our climate is dying and humans don't care and it's all about money and wealth," Madeleine said. "We should be running on solar and wind farms."
Adults also addressed the crowd, including Blue Mountains MP Trish Doyle, who said she was "blown away by the turnout" and "I stand with you."
Many of the students were also travelling into Sydney for the rally planned at noon at Town Hall.
The movement calls for all politicians to take urgent action to stop the climate crisis. They are against the Adani coal mine and new fossil fuel projects, and want Australia to be powered by 100 per cent renewable energy by 2030.