Holland's largest teachers union is on strike today against a bill that will increase teachers' working hours and cut their holidays. They are also protesting against cuts to special needs education, a salary freeze and the introduction of performance-related-pay. The biggest Dutch teachers union, AOb, have said that 20,000 teachers are taking part in the strike, which will affect over 600 schools. There will also be a mass rally in Utrecht to protest the changes. The teachers say that, without increased funding for more staff, the extra hours will mean students will be sat in classrooms without supervision. But despite protests of several thousand students in Amsterdam at the end of last year and a three day strike earlier this year by a smaller union, the bill has been passed through the lower house of parliament. The protests today aim to stop the bill from being passed by the Senate.