Now, these textbooks are used in about1,200 United States elementary schools, with annual sales of about 100,000copies.

Building on this growing popularity, representatives from Singapore'sEducation Ministry and publisher Marshall Cavendish were at the SingaporeEmbassy on Tuesday evening to launch a treatise on the thinking behind thetextbooks.

'We know that the US has always been interested in (Singapore'sway of teaching) mathematics, so with the monograph being written, we decidedwe would come here to officially launch it and take the opportunity to explaina bit about the differences between our curriculum' and that of America, saidMadam Low Khah Gek, director of the ministry's curriculum planning and development division.

Sceptics have often questioned the relevance of theSingaporean model to the US, particularly given the differences in the size andculture of the countries and their education systems.

The population ofSingapore, for instance, is only slightly bigger than that of Los Angeles, thelargest city in the state of California.

But exploratory studies by US mathsacademics have found over the years that students in the US who adopt theSingapore model, together with the right training for teachers and some tweaksto fit the local context, have outperformed their peers who stuck with UStextbooks.

Interest in the Singaporean textbooks grew further in late 2007,when California endorsed their use for elementary schools statewide.

Elementary schools in states such as Massachusetts, New Jersey and Wisconsinare also said to be using the textbooks.

'This is quite a change in the US,'said Dr Alan Ginsburg, director of policy and programme studies services at theUS Department of Education, when he spoke at the Singapore Embassy on Tuesday.

'Ten years ago, you would not see the US looking outwards. That haschanged.'

President Barack Obama also drew attention to Singapore's model ina recent speech on educational reform, remarking: 'In 8th grade math, we havefallen to 9th place. Singapore's middle-schoolers outperform ours three toone.'

Ms Duriya Aziz, publisher and deputy general manager of MarshallCavendish, said growing interest means US sales of the Singaporean textbooksshould grow 'exponentially'.

CHUA CHIN HON