A headteacher is quitting the profession after 23 years over claims schools are now "factory farming" children and failing to prepare them properly for a successful future.
In an impassioned resignation letter, Kit Messenger, of Manor Field Primary School in Burgess Hill, West Sussex, criticised the "progressively fragmented educational system".
And, in a withering attack on education policy, she laid into moves to narrow the curriculum, which she said had led to schools being judged on only reading, writing and mathematics.
Ms Messenger, 45, said the Government's push for schools to become academies reinforced her belief to quit 530-pupil Manor Field - a decision she described as "heart-breaking".
She also admitted finding it difficult to protect her staff from heavy workloads that left them little time outside the classroom for their families.
And, in a brutally honest assessment of the education system, she said the toll of completing "bureaucratic tasks" had affected her own physical and emotional health.
In the letter, she said: "Unfortunately, despite all of your support, in the current educational climate I no longer feel it will be possible to achieve my vision for children at Manor Field School.
"The narrowing of the curriculum, to the detriment of all other subject areas, has increased significantly over the past two years.
"Judgments made of schools are now so restricted to a small set of measures that the pressure to focus only on reading, writing and mathematics has become untenable and I have increasingly felt that we are 'factory farming' our children and failing to prepare them adequately for a successful future in this changing world.
"The recent announcement that all schools should become academies has further strengthened my belief that now is the time to leave a career that has been central to my life for 23 years.
"I strongly believe in a state system in which all children have access to a good, rounded education and where staff are treated with respect and enjoy fair working conditions. I do not believe this will be possible under our progressively fragmented educational system.
"I have been passionate about my career for more than 20 years, putting it ahead of everything else in my life. My love for teaching and school improvement has run like blood through my veins and I have constantly sacrificed friendships and family life in order to secure better provision for children.
"I now find that much of my work is spent completing bureaucratic tasks which have no or little positive impact on our pupils and this has left me feeling increasingly frustrated and unhappy. It has now begun to have a detrimental impact on my physical and emotional health.
"I have also found it progressively difficult to protect staff from workloads that leave little time for their own families, feeling that the only way to secure good outcomes at inspection is to push them further than I believe is reasonable.
"The decision to resign from the post of headteacher and bring to an end a career that I have loved so very deeply has been incredibly difficult. It is no exaggeration to say it has been heart-breaking. However, I do know it is the right decision."