A Birmingham headteacher has launched a blistering attack on SAT tests, comparing them to "child abuse".
Maureen Hinckley, of Tiverton Junior and Infants, said youngsters felt "threatened and intimidated" by the exams.
And she warned many schools were using "devious" means to select pupils who would improve their SAT scores and boost their way up league tables.
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Ms Hinckley's comments came as thousands of 11-year-olds sit national Key Stage Two tests in numeracy, literacy and science this week.
It follows claims by the Association of Teachers and Lecturers that national tests at primary level, were "demotivating, stressful and alienating".
It also coincided with the Government's exams watchdog, the Qualifications and Curriculum Authority, last night raising the prospect of ending externally marked tests for 11 and 14-year-olds.
Ms Hinckley, whose Selly Oak-based school contains a high proportion of pupils with behavioural and social problems, said: "We had a science paper this morning. It was unbelievable.
"Many heads I speak to would describe it as child abuse. It was one where they felt threatened and intimidated. It was not compatible with their wellbeing at all.
"The pupils were horrified. I invigilated and I saw the look on their little faces and it was pitiful. They looked at me and I felt as if I had let them down. If I had delivered a lesson that was as distressing and irrelevant to them as this was, I would have been deemed a failing teacher."
Ms Hinckley said it was "lunacy" her school was judged against an admission-setting faith school such as a Church of England school located in a well-to-do suburb.
"I have only 14 pupils children taking the exam. By the time you take the special needs pupils out and those who live with drug addicts and alcoholics or didn't have a good breakfast, what chance do I have of hitting the floor target?"
Ms Hinckley, a teacher of 35 years in Birmingham, claimed many schools were effectively carrying out a back door admissions policy by avoiding taking on difficult pupils.
"I have four pupils who have been excluded from other schools and a further half a dozen who would have been excluded who have been moved on. On top of this I have children who have moved into the area and have been to other schools and when it is apparent they have challenging behaviour or they have the word levels that won't be compatible with SAT results, they are not offered a place."
Ms Hinckley's concerns echo findings of a study by the Sutton Trust. It found the proportion of pupils on free school meals at the country's top 200 secondaries was less than half that of their postcode area. The Department for Education and Skills defended the five hours and 15 minutes worth of tests Year Six pupils will be put through this week.
"National tests are an integral part of effective teaching and learning, helping to identify pupils that need extra support as well as those with talents that need to be stretched," said a spokeswoman. Children sit just three sets of national curriculum tests during their 11 years at school.
"Teachers are accustomed to ensuring that their children know what to expect and can cope well with the tests."
A Birmingham City Council spokesman said: "No Birmingham primary school can reject the application of a pupil under the grounds of social status, nor can they exclude a pupil without following the correct procedures. Therefore any evidence of schools not following the correct guide-lines will be challenged by the LEA."
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