By Sean Coughlan
BBC News Online education staff
School tests are most useful for children from poorer backgrounds, says the School Standards Minister, David Miliband.
Teachers have threatened to boycott national tests next year
Defending the use of national tests from MPs concerned about "over-testing", Mr Miliband said that tests were helping to drive up standards - and if they were scrapped "it would be the poorest children who would lose out".
And he said that he was "passionate" about using the tests to keep pupils on the path to success later in their school careers, including those who might have slipped into underachievement.
The minister, facing threats of a boycott of tests by teachers, highlighted the strong link between success at primary tests and the qualifications which would affect their later "life chances".
If children reach the expected levels at the age of 11, he said that there was a 70% chance that they would get five good GCSEs. And among pupils who failed tests at 14, he said that there was only a 5% likelihood that they would achieve five good GCSEs.
Facing questions from the cross-party Education Select Committee, Mr Miliband said that the testing system was under attack from different political directions.
"The traditional right says that there are bright kids and thick kids - and there's nothing you can do about it," he said.
And he said that there were other critics who believed that the government's efforts to raise and measure standards were "meaningless".
David Miliband said that parents would expect school information to be published
But getting rid of the testing structure, he said, would mean a return to a school system where it was assumed that pupils' abilities were unlikely to change from year to year - an attitude which had in the past allowed many poorer pupils to underachieve.
The most common characteristic of underachieving schools remained an intake from a deprived area, said the minister. And the use of tests and targets was helping to monitor and tackle this inequality, rather than accept its inevitability.
Teachers' unions have been strongly opposed to the testing system - and this year's annual conference of the National Union of Teachers threatened a boycott of next year's tests.
And the committee chairman, Barry Sheerman, reflected that there had been claims that there had been an over-emphasis on testing, which was stifling teachers' creativity.
David Chaytor also questioned whether the assessments could be carried out by teachers, rather than applying the pressure of external tests. And he argued that the tests contributed to the "polarisation" of schools through success or failure in the league tables.
But Mr Miliband rejected the suggestion that England should follow Northern Ireland and Wales in scrapping league tables, saying that parents would expect to have access to the information gathered about schools.
"It's no longer possible for professions to say that we have data showing the differences between institutions, but we're not sharing it with the great unwashed," the school standards minister said.
Also facing questions from MPs, was the Schools Minister Stephen Twigg, who raised the prospect of more support for ethnic minority pupils.
For pupils who do not have English as a first language, this could include more opportunities for learning in their mother tongue, until they learn English.
And he said that there had been positive results from schemes targeting specific ethnic groups, such as raising standards among Bangladeshi pupils.
The ministers were also challenged over teacher shortages, with the Liberal Democrat Paul Holmes saying that the improvements claimed by the government were "masking" a crisis in staffing levels.
Mr Holmes said that more and more teachers in their fifties were quitting - and that the government's recruitment figures were padded out with overseas teachers and part-timers.
Mr Milband resisted attempts to draw him into discussing the problems with school funding, other than to re-state the government's position that over £500m had still to be allocated by local authorities.