Up to 20,000 schools are set to be hit by strike action on Friday as thousands of teachers defy a call from David Cameron to call off industrial action. As many as four in five schools could be closed either wholly or partially as teachers join a dispute over public sector pension reforms. Up to 750,000 teachers and civil servants are expected to walk out in protest at proposed changes to their pensions, causing chaos in schools, airports, job centres and courts. The industrial action believed to be supported by more than 100,000 teachers, one in eight is the first national teachers\' strike in 25 years and will affect about seven million children. The Prime Minister told public sector workers strikes were ‘wrong\' at a time when discussions were ongoing, pointing out that their retirement funds are costing every household in the country £1,000 a year and must be reformed. With the lives of millions of working families due to be disrupted, Mr Cameron said changes being proposed for state employees were a ‘good deal,\' and he insisted that their pensions would remain ‘much better\' than those of most people who work in the private sector. He insisted there would be no U-turn on plans to cut the costs of ‘gold-plated\' pension schemes, and told teachers, nurses and police officers they were being given ‘really bad advice\' by unions. The Prime Minister told state workers that striking would be: \"Wrong for you, for the people you serve, for the good of the country.\" From / Gulf News