A greater emphasis on correct spelling would not only teach children how to write accurately but also improve their comprehension, powers of expression and understanding of meaning and grammar, author Jennifer Chew says.
Mrs Chew, a teacher at a Surrey sixth-form college, cites recent studies, including a survey earlier this year by the Basic Skills Agency, as confirmation that standards have fallen.
While parents and employers value accurate spelling, the educational establishment has misdirected its energies towards the communication of meaning, she argues. Examiners' willingness to tolerate bad spelling and punctuation, and the rise of coursework, which allows mistakes to be corrected during redrafting, have perpetuated the downward trend.
The pamphlet, the first in a series by the CPS this summer, traces the failings identified among 16-year-olds back to the methods used to teach literacy in primary schools.
It calls for a systematic teaching of the alphabet, and the sounds the letters represent, arguing that "if most English spelling is rule-governed, it is unfair not to teach children the rules".
Children should be able to identify each letter or group of letters, rather than recognise the entire word by its first letters or shape on the page.
While most primaries claim to use a mixture of methods, in reality phonics-based ones are used little, it adds.
Spelling Standards: How to correct the decline, by Jennifer Chew, costs Pounds 5 and is published by the Centre for Policy Studies, 52 Rochester Row, London SW1P 1JU