
Young people across Europe have been skipping school to march in protest about climate change.
Their protest is inspired by 16-year-old Swedish student Greta, who performs a school strike every Friday to protest in front of the Swedish parliament.
Protests have been taking place since last week in many European cities and as far away as Australia.
In Belgium alone last week, the protest movement numbered around 12,000 young people, all participating in a school strike.
According to police on Thursday, that figure increased to an estimated 35,000 young protesters.
Meanwhile, other schools asked permission from parents and organised it officially.
(CBBC Newsround)