Many teachers hate Sats - the tests for children at ages seven, 11 and 14.
They say the exams put unreasonable pressure on teachers to reach targets, narrow the curriculum to mere testing of literacy and numeracy, and generally make education an unpleasant experience for children.
The National Union of Teachers (NUT) has voted to boycott Sats.
Hazel Danson, a teacher of six and seven year olds at Clough Head Infant and Junior School in Kirklees, West Yorkshire, is in a good position to judge the effects of Sats.
 | I'm ashamed, because I look back and see how some of the children who have gone through my care have suffered |
She qualified in 1990, the year the pilot scheme started, as part of the then Conservative government's setting-up of a national curriculum. Ms Danson, one of the many outspoken opponents of Sats at the NUT's national conference in Harrogate, North Yorkshire, said: "The situation is just ridiculous. The tests are dreadful and something needs to be done.
"When I first came into teaching, the national curriculum was in its infancy.
"Even then, people were predicting the damage tests were going to do, but, of course, we didn't have the evidence to prove it."
In 1993 the NUT was among a group of unions which boycotted testing.
This went on for two years, but gradually support dwindled.
Ms Danson said: "You could have predicted the narrowing of the curriculum that centralised testing would bring.
"Children who do not reach the required level at age seven are made to feel they are failures.
"I've no objections to assessment. That's part of the role of a teacher, after all.
"But the best way is for it to be in school, without all this pressure.
'Damaged'
"I've had children crying over the tests. It just makes me so angry.
"In fact I'm ashamed, because I look back and see how some of the children who have gone through my care have suffered.
"I'm ashamed because I was made to do this to them and I, as a result, have damaged them."
Clough Head school, which is in a rural area and has only 87 pupils, is under less pressure than larger inner-city institutions, according to Miss Danson.
She said: "At my school we are trying really hard to try to make sure the breadth of the curriculum is maintained.
"But we have to be determined to do that. There is pressure from the local authority, school inspectors and all sorts of people.
"But, even with a large school, there are unlikely to be more than 60 pupils in a year.
'Disastrous'
"So, one or two pupils' results will amount to a few percentage points' difference in the Sats score.
"As for us, one pupil can make a 10% difference, so what's the point of having to reach targets?"
Ms Danson added: "We want to keep the testing as low-key as possible and not worry the children about them.
"Some kids have seen more of the world than they should at age seven. What they need is the broadest curriculum possible.
"The effects of Sats for them are disastrous. All kids deserve a rounded educational experience.
"Sats damage that and that's why we have to boycott them."