Schools in England spend "insufficient time" teaching about the British Empire, education watchdog Ofsted has warned.
The Empire receives "insufficient time" in schools, Ofsted has warned
Time given over to teaching 11 to 16-year-olds the "significant subject" could be just a few lessons in five years, inspectors found.
Some schools devoted lessons to the question of what history was instead of teaching the subject's actual content.
Teachers were also urged to raise awareness of the Empire's "controversial legacy".
For some 11 to 14-year-olds the topic could be included in a unit covering British history from 1750 to 1900.
But that was only one of six units expected to be taught and it included other material aside from the Empire's growth.
An Ofsted spokesman said that, in the "limited time available", selected content should "be significant".
"The British Empire is given as an example of a significant subject that
currently receives insufficient time in many schools", she said.
"Pupils should know about the Empire and that it has been interpreted by
historians and others in different ways."
Ofsted's intervention has pleased educational traditionalists who say the growth of the Empire is "a very important period of British history".
Nick Seaton, chairman of the Campaign for Real Education, said: "The key point is that the Empire was very beneficial to indigenous populations in many ways, even though it had its faults.
"The nice thing is that a lot of ex-colonial populations still think quite well of the British."
The Ofsted report on the teaching of history in 2002/2003 also found that some schools were devoting too much time to teaching about Nazi Germany and other subjects.
Ofsted said secondary schools could not say they did not have enough time to cover more ground in history because the subject matter of some lessons was "hard to justify in terms of significance".
"Schools can hardly complain that there is insufficient time for history if they have not first considered the best use of every lesson that they teach in order to achieve their aims and objectives", the spokesman added.
But the Secondary Heads Association said that because history was such a broad and deep subject it was inevitable some parts would get less coverage.
General secretary John Dunford said: "It is important that schools concentrate on the most important and interesting aspects of history, and I think they do that."