What makes 4 such a magic number? In the past few weeks heads, governors and local authorities have received high-pressure letters from the Department for Education and Skills urging them to make sure more children attain this holy grail.
It has been claimed that children cannot cope with the secondary school curriculum without level 4 in English, and even that the 25 per cent of children who missed it last year cannot read. Do today's ministers understand the tests they are putting such faith in?
What is the difference between levels 3 and 4? A child who has reached level 3 probably reads as well as plenty of adults whose main literary diet is the least demanding tabloid newspapers. They do not have a problem with basic decoding. They can read a range of texts fluently, understand the main points and express preferences.
The big difference is that a child who has reached level 4 can read between the lines, says Marian Sainsbury, who develops the national tests at the National Foundation for Educational Research. They can use inference to work out why characters have said or done particular things, and take an overview of the whole story. They can make better use of information they find in books or on the Internet.
Literacy specialist Sue Palmer believes the difference goes deeper. "If you have access to more complex forms of language you can access more complex and abstract ideas," she says. For instance, a child at level 3 can understand what a comma is, while at level 4 they understand what a clause is. That means they are able to think and write in more complex sentences.
"Literacy is not just about reading and writing in a literal way, but how it changes the way you are able to think," she says.
So it seems that level 4 really does represent a tipping point between basic reading skills and real literacy.
Given the complexity of the secondary curriculum, with its emphasis on authorial technique, interpretation and use of textbooks, a child who has not got level 4 skills could well find themselves struggling, say experts.
But this does not mean that many will not catch up, or that every child can and must reach level 4 by 11 or 12.
Secondary schools should be able to cater for all sorts of pupils. All this begs a number of questions, though. What does "borderline" mean? Huge amounts of money, time and effort are spent trying to help youngsters over that hurdle.
Since tests cannot be 100 per cent accurate, children just on either side of this boundary may well be much the same.
Little things can add those crucial few points, such as having learned what subheads are for in information writing.
Many teachers are concerned about all this test preparation, with some children being made to do more of what did not work for them in the first place, while for others, their level 4 represents a test result but no real knowledge and understanding.
"A significant number have been coached into a level 4," says Sue Palmer.
"Until we are properly addressing literacy and not test results, we will be doing our children a disservice."
The Qualifications and Curriculum Authority shows how a sample writing test would be marked on its website, www.qca.org.uk
* Shifts in time and place help shape the story and guide the reader through the text, for instance by introducing a new section to draw attention to the main event ("After seeing all the statues"; "Meanwhile, back on Earth"). Paragraph transitions may be awkward.
* Within paragraphs, connected sequences of events may be developed around a sentence.
* Relationships between paragraphs give structure to the whole story, for instance contrasts of mood, shifts in time, changes in location.
* References to characters and events are varied, for instance avoiding repetition by omitting words. Paragraph structure is controlled to shape the story.