It is simply harder than reading. It may be difficult to catch the subtleties and nuances in a text you're reading, but it's much tougher to get the inflection and tone just right in your own articles and stories - or memos to the boss.
English spelling can be hard to decipher, but it's so much more difficult to keep track of all its irregularities when you're trying to write. And it's certainly easy enough to laugh at the wit in, say, Roald Dahl, and appreciate what makes him funny. It's stunningly hard trying to be funny in print, without those mannerisms, tones of voice and facial expressions you can use when speaking.
But if it seems logical that children should score higher in the reading SATs than in their writing tests, that doesn't explain why the gap is widening. Last week's figures show that Year 6 reading results went up by 5 per cent (to 83 per cent), while writing increased by only 1 per cent (to 55 per cent).
Writing is harder to teach, as well as harder to do, and this is something the National Literacy Strategy has not properly accounted for, until now.
The literacy hour's structure is less well-suited to writing - although government officials are now encouraging schools to use more flexibility - and there has not been enough advice and information about how to teach the writing components effectively.
Now they are remedying that, with a massive training programme for junior teachers, called Grammar for Writing, to be followed next year with an infant version.
It is fair to say that schools have not always taught writing well in the past, and these courses are intended to help give teachers, and through them children, the tools for writing. The idea is that understanding how sentences are put together mkes it easier to get across your ideas and forms a foundation for self-expression and creativity - just as you need the right tools to build a fine piece of furniture or to carve a sculpture. The training video shows classes from socially mixed schools becoming deeply involved in textual analysis, tossing ideas to and fro, and coming to grips with what it takes to convey your point, a particular mood, or a character's personality.
So let us dismiss any niggling suspicion that it all has something to do with meeting David Blunkett's targets for 2002, and praise the Government for recognising that writing is a full third of the 3Rs and stepping in to do something about it.
But creativity also needs space and air, and the chance for developing writers to bloom in their own ways. Will children working intensively all morning on literacy and maths, as they now do across the nation, and then having to take in seven subjects in the afternoon, have that space for creativity? And what about the increasing pressure to catch up in the writing SATs? Last year's Write Away autobiography competition had too many entries that were technically competent, but didn't sparkle with imagination and daring.
Last week saw the publication of Write Away 4, for key stage 3 in The TES and for juniors in TES Primary. The Write Away packs include short autobiographical pieces by well-known authors such as Jacqueline Wilson, to help inspire children's work. I hope that more schools will give their pupils the time and space to shine, and send in a cartload of diamonds.
Diane Hofkins is editor of TES Primary. The October issue of this monthly magazine is now on sale at newsagents, price pound;2. In addition to Write Away, it includes a Writer's Toolkit poster. To subscribe visit www.tesprimary.com.
Write Away 4 is available on www.tes.co.uk and wwwtesprimary.co.uk