Lynne Truss, bestselling author and punctuation pedant, says that children are being let down by schools' failure to correct their grammar.
The author of Eats, Shoots Leaves says: "There just isn't enough emphasis on writing in the school system - not enough correcting of errors; not enough enthusing about the mechanics of language."
Ms Truss has written a 16-page illustrated version of her book (Eats, Shoots Leaves: Why, Commas Really Do Make a Difference!) for primary pupils, showing the importance of using commas correctly. Illustrations demonstrate the way 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" is accompanied by a picture of all three skipping together, Grandma waving her walking frame as she leads the way.
Ms Truss said assuming that children would absorb grammar by osmosis was similar to expecting them to learn a sonata merely by fiddling with the piano keys. "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'.
"It's similar to music. You don't just pick up how to play the piano. I feel kids are being let down, I really do. In a communications age, knowing how to write is a life skill," she said.
Many teachers, however, appear to disagree with Ms Truss's diagnosis of the need to instruct pupils in grammar, punctuation and spelling.
A contributor to The TES online staffroom has started two threads, one stating that spelling and grammar do make a difference, the other saying that they do not.
The pro-punctuation lobby has produced three pages of well-parsed reasoning to date. The anti-grammar thread, however, extends to some 20 pages. One contributor moans: "Some people prefer not to live by pointless rules imposed by dreary people: 'do not step on the grass'; 'you must wait until the green man flashes'; 'never misuse apostrophes'. . ."
Eats, Shoots Leaves: Why, Commas Really Do Make a Difference! is published on September 14.