RIO DE JANEIRO (AP) — It was when the tear gas canister rattled around at her feet and a masked young man picked it up and tossed it back at police that kindergarten teacher Andrea Coelho decided she was for him and his fellow Black Bloc anarchists.

Coelho was one of thousands of teachers marching through central Rio de Janeiro to demand better wages and school conditions when police decided to disperse the demonstration. A few nights before, striking teachers occupying the city council building were beaten and dragged out by officers.

"It was the Black Bloc that protected me in that protest," Coelho, 47, said at the beginning of a march last week that again descended into fighting between anarchists and police. "The police came in firing tear gas, hitting us with clubs. A young Black Bloc stepped right in between me and the police. If it weren't for them, the police would have destroyed us."

That sentiment has helped turn the anarchists in Brazil into a driving force behind protests in recent weeks. The demonstrations have lessened in size but not frequency since masses took to the streets in June, fed up with a litany of problems that mostly center on corruption, woeful public services, and big spending on the upcoming World Cup and 2016 Olympics.