Ofsted says tests narrow learning
Ms Gilbert's warnings have been ignored by some schools
England's education inspectorate, Ofsted, says some schools narrow the curriculum by "teaching to the test".
Chief inspector Christine Gilbert wrote to a Commons select committee, drawing on inspection evidence to bolster comments she had made.
Her remarks are given added bite by the furore over delayed test results, and renewed questioning of the value of the "Sats" children take at 11 and 14.
Schools Secretary Ed Balls said teaching to the test was wrong.
Ms Gilbert's letter to the MPs on the committee was sent a month ago but has just been published. Their report on the assessment system had supported the idea of national tests, but said an "over-emphasis" on results could distort how children were taught and compromise their access to a balanced education.
In the letter, Ms Gilbert says the most successful schools "focus on national testing and assessment without reducing creativity in the classroom".
"However, in some schools an emphasis on tests in English, mathematics and science limits the range of work in these subjects in particular year groups."
These are often Year 6 and Year 9 - in which children take their Sats.
Teaching is sometimes too narrowly focused on exam techniques at the expense of understanding, she says.
This is not a new warning from Ofsted - what is clear is that schools are ignoring it.
As Ms Gilbert puts it, more recent evidence "suggests the continuance of these trends".
Some schools complain they are pre-judged by Ofsted inspection teams on the basis of their pupils' results.
Concern about this has added to the volume of complaints from schools about the lateness and alleged unreliability of this year's results.
Ms Gilbert says Ofsted "does not rely on published test data alone".
Mr Balls told the MPs last week that in his view the majority of teachers are not "teaching to the test".
He said: "Where it is happening, it is the wrong thing to do. The new curriculum should be broad and engaging, we are embedding creativity into the curriculum.
"A well-rounded understanding of the subject is a better preparation for the test. Part of learning is the ability to reproduce it in the exam.
"The principle of externally-assessed tests is the right one - the question is how best to deliver that."
More results due
On Tuesday, another update is due on the results website for schools from the test contractor, ETS.
By the last update, last Friday, 29% of the results of English tests taken by 14-year-olds had still not been issued.
ETS said 93% of pupils' maths results were available and 91% of science. About one in five primary schools had still not received a full set of marks.
No equivalent figure was given for secondary schools.
Marking is still going on. Some markers have not been able to enter marks into ETS' online database.
Some schools have had unmarked scripts returned to them.
Others say they do not know the whereabouts of their bundles of scripts.
The National Union of Teachers is one of the unions opposed to the testing system.
Its acting general secretary, Christine Blower, said: "The current unwieldy testing system, which is this summer now in crisis, highlights the obvious.
"All of the evidence points inexorably in one direction; that of the government suspending the current national curriculum testing arrangements, and commissioning a fundamental and independent review of the tests."
An inquiry into what has gone wrong is being conducted by a former chief inspector, Lord Sutherland.
The Tories have announced their own inquiry into the whole examination and testing system in England.