But now, according to a new report, commercial worksheets are eroding the old principle - and maths is suffering as a result.

A primary school study by the Office for Standards in Education found that pupils no longer scribble on the side of the page to support their answers. The problem was particularly marked in key stage 1. The report said:

“Whilst pupils record accurately using conventional signs and symbols, the use of recording as an aid to calculation is a weakness.”

It continued: “In some instances, worksheets limit pupils’ opportunities to record their mathematical thinking in a manner which makes sense for them and which might support their oral explanations later.”

Inspectors also said calculators were not being used enough in key stage 2, pointing out that they are a useful tool for teaching numbers and the number system.

“Despite its potential value, the use of the calculator is not a regular feature in the teaching of the daily maths lesson,” the report said.

However, it warned that calculators should be used with other techniques such as effective questioning, otherwise “calculator work can become a mechanical exercise with insufficient emphasis on pupils’ understanding of the underlying processes”.

The report also found that not enough attention is given to helping pupils to solve problems expressed in words rather than numbers.

And the strategy of estimating the correct answer before tackling a problem in detail is not used enough, so pupils are unable to check if answers are sensible.

But inspectors found that in the two years since the introduction of the national numeracy strategy, schools had made “significant progress” in maths teaching, particularly in mental calculation.

OFSTED’s report can be seen at www.ofsted.gov.ukpublicdocs02calculation.pdf