France's pupils and teachers have gone back to school this week in the annual ritual known as the 'rentrée scolaire'. Amid the usual hopes and expectations for the new school year, many teachers feel a growing sense of frustration. For despite the promise by President François Hollande to make education a priority and create 60,000 new teaching posts, many current staff feel their working conditions and pay have been overlooked. In some deprived areas, meanwhile, hard-pressed teachers have been voting with their feet, asking to be transferred to less challenging regions. Here Mediapart examines the situation in three of those vulnerable education authorities, who have been forced to take on thousands of trainee teachers to fill their classrooms this year. Thomas Saint-Cricq and Lucie Delaporte report.