THE Professional Teachers' Union is investigating claims that a school has broken the law by requiring its teachers to sign new contracts promising to pass the language benchmark test by 2004 - one year ahead of the 2005 deadline. Without naming the school, Babie Chik Pun-shing, the union's education and information technology co-ordinator, said: 'We are investigating whether the contract can over-ride the Government's Code of Aid, which governs all aided and public schools. 'According to a complaint letter filed by a group of teachers at that school, the principal won't even allow them to meet the benchmark by completing a training course.' It is not known if both English and Putonghua teachers at the school are being asked to sign up. The assistant director of the Education Department, Tam Chun-kit, said recently that schools could consider adding new contract terms relating to the benchmark test.