Thousands of striking teachers and their supporters clashed with police Monday night in Rio de Janeiro after a small group of protesters threw fireworks, grenades, and tear gas. Police responded by firing tear gas into the crowd. Masked protesters also destroyed banks in a surrounding area and lit a bus on fire. Teachers have been calling for better pay and an overhaul of the country’s educational system, while some said Monday’s protests were part of a larger social movement in the wake of Brazil spending money on the Olympics and the World Cup instead of on public works. Police said 10,000 demonstrated, but the teachers’ union estimated that it was closer to 50,000.