Are the national tests failing our children?

School tests have begun in earnest. But constant changes make the system unreliable.

They were the tests that would tell parents how their children were performing compared with their classmates and national standards. They were the tests that would, for the first time, measure national standards of achievement. And they were the tests that would tell us whether standards were rising or falling.

Yet five years after the first tests for seven-year-olds were introduced, three years after 14-year-olds sat down to the first national tests and in the second year of the 11-year-old tests, we are not much wiser about the state of our schools.

The reason is easy to fathom. Since the tests were first introduced there have been constant changes not only to the tests themselves but also to the standards by which they are judged.

They are not all getting harder as ministers show off their determination to drive up standards. Nothing so simple. Some of them are indeed getting more difficult. But some are getting easier. And some are just getting different.

Take the tests for 11-year-olds. Results published earlier this year caused an outcry when it was revealed that around half of pupils had failed to reach the expected standard in maths and English.

Results of this year's tests will be awaited eagerly. Standards are rising, commentators will say, if they are better. Or, if the results are much the same, standards are still bad. Yet the truth is that no-one will really know.

Most 11-year-olds are expected to reach level 4 with the above average reaching level 5, the below average level 3 and the really brilliant level 6.

But last year in science, a much higher proportion of pupils were awarded the higher grades or levels than in English or maths. So this year, it will be harder to get level 5 because more challenging questions have been included - in other words it has been made more difficult.

In English this year there will be a separate paper for pupils thought to be at level 6 so that those aiming at the other levels will have less to read in the comprehension and will not be put off by the most flummoxing questions. This could make English slightly easier.

And in maths, pupils will be forbidden to use a calculator in one paper this year. The results may provide fodder for any number of interesting theories about the state of the nation's mental arithmetic but they will not be strictly comparable with the previous year.

The picture for 14-year-olds is less confusing. Maths and science have settled down, with most teachers confident that they give a fair ideas of pupils' ability. English is different. The School Curriculum and Assessment Authority has acknowledged that markers last year failed to award high enough marks to some of the brightest pupils. This year, markers are being specially trained to ensure that they can tell their level 7 and 8s from their level 6s. (Most 14-year-olds are expected to reach between level 5 and level 6.) Put bluntly, this means that some candidates who received level 5 or 6 last year would have reached level 7 or 8 this.

Even the seven-year-old tests, which have undergone a series of transformations since their introduction, are changing once more. Until now, pupils who reached the lowest level in reading have had to recognise simply that words carry meaning and that print runs from left to right. Now they will be expected to read a few words. The logic of this may be impeccable but it does mean it will be harder for pupils to reach level 1. Stand by for the "Reading standards shock" headlines.

This year, too, seven-year-olds will, for the first time, be offered an optional test that will give them a score for reading related to their age and to the scores of other pupils, very similar to the old-fashioned reading age in use in schools for decades.

Reading ages, whatever their faults, have a currency and stability which the new tests lack. Parents and teachers may wonder if the testing wheel has come full circle and whether that is necessarily a bad thing.