Expecting children to pick up the rules of grammar through reading is like expecting them to learn a sonata by fiddling with the piano keys, according to Lynne Truss, bestselling writer and punctuation puritan.
The author of Eats, Shoots Leaves insists that punctuation rules are similar to those of music notation and should be taught in schools accordingly.
"People can read very widely and well, and are still not able to spell, or construct a sentence, or work out whether there's an apostrophe in 'its',"
she said. "It's similar to music. You don't just pick up how to play the piano. I feel kids are being let down. In a communications age, knowing how to write is a life skill."
Schools, she says, tend to assume that pupils will learn grammar as they read. "Why isn't learning to write a bigger part of the curriculum?" she said. "I really don't understand."
Ms Truss was speaking to The TES prior to the publication of a primary-school version of her book. Eats, Shoots Leaves: why, commas really do make a difference! is a picture-book showing the importance of using commas correctly. Illustrations demonstrate that carefully positioned punctuation can change the meaning of a sentence.
So a picture illustrating the sentence, "After we left Grandma, Mummy and I skipped about in the park" shows a child and her mother skipping through the park as her grandmother watches from a nearby bench.
Opposite, the sentence "After we left, Grandma, Mummy and I skipped about in the park" has a picture of all three skipping.
Ms Truss believes it is vital that children gain a basic understanding of grammar at primary school.
"Many adults feel completely at sea when they have to communicate in the written form," she said. "But, with the rise of the internet and email, this is something they probably have to do all day, every day. Everyone's a writer."
And, she says, the notion of following a writer's voice through the printed word is disappearing: "For 500 years, people have written for print, and known how to read print. Now, people read from screens and write for screens. These are quite different skills."
But Paul Wagstaff, director of the national primary strategy, insists that pupils are given a good grounding in grammar. "We have a key focus on developing punctuation and grammar, alongside composition and content," he said. "Literacy standards have risen significantly recently. It's difficult to see how that would have happened without an emphasis on all the elements that make an effective writer."
There was little grammar in Ms Truss's schooling at Tiffin girls' grammar, in Kingston-upon-Thames ("though English O-level did have some parsing in it, I think"). Her love for punctuation emerged when she worked as deputy literary editor at The Times Higher Education Supplement. She would devour its style guide, marvelling at the difference between "Lloyds" (the bank) and "Lloyd's" (the insurer).
"It's about the printed word - how printers devised marks to help readers to understand precisely what the writer intended," she said. "I'm worried that when people don't know how to read books any more, they will look at a page of Jane Austen and not understand why it's presented in the way it is.
It will be like us looking at the Rosetta Stone."
Eats, Shoots Leaves: why, commas really do make a difference! is to be published on September 14 by Profile Books