Thunberg, who was recently nominated for the Nobel Peace Prize, was cheered for her blunt message to leaders at the World Economic Forum in Switzerland this year, when she told them: "I want you to panic".
That conversation is likely to get louder, with several US presidential hopefuls planning to campaign on climate change.
The 11-year-old, identified only as Lily, read aloud an open letter asking the government to take immediate action on air pollution, single-use plastics, climate change and deforestation. "Why should we go and study for a future that may not exist anymore?"
Climate change action was something students needed to "keep momentum on", he said.
It was also great to see young people heading the strike, as it showed young people were willing to create change in the area, Leggett said.
Protesters call for the mayor to make an appearance from Seymour Square, opposite the Marlborough District Council building.
The protests are part of a movement inspired by Greta Thunberg, a 15-year-old Swedish schoolgirl who has been missing lessons to sit outside government offices in her country in a bid to persuade lawmakers to comply with the Paris climate agreement. The youth of this world has started to move and we will not rest again. The English Schools Foundation (ESF) said that it can not endorse an action that threatens to compromise student safety.
Holly Gillibrand, 13, has been taking similar action at Fort William's Lochaber High School since January.
One parent in attendance said that about 1,000 kids are at the strike, with more "streaming in" all of the time.
The children have been chanting: "What do we want?"
More than 1000 school pupils have turned out for the protest in Edinburgh.
Hirsi, who lists on Twitter page that she is the head of the Minnesota High School Democrats and several other left-wing youth-based organizations, said in a recent interview with Grist that she is looking to "change the conversation" on issues such as the Green New Deal by organizing the strike.
"We are the professionals and we're saying the young generation is right", said Volker Quaschning, a professor of engineering at Berlin's University of Applied Sciences.
Home schooled students from Blenheim Natural Learners Co-op with signs they made in support of the climate change protest.