There is monumental evidence of the benefits of teaching in smaller classes, particularly in the earliest years of primary school, two of the world's leading experts in the field told a conference at the Hong Kong Institute of Education yesterday. The conference comes ahead of a key debate on the issue in a Legislative Council panel tomorrow, at which Education and Manpower Bureau officials are expected to argue that government research has so far proved inconclusive. 'We have monumental research evidence that small classes make a major difference in student work and how students behave, and yet we continue an argument that seems futile,' said Charles Achilles, professor at the College of Education and Human Services at Seton Hall University, New Jersey. Professor Achilles said his studies had found students placed in smaller classes from kindergarten were 'almost a full year' ahead of other children four years later. 'You have got to get the kids early,' he said. Peter Blatchford, a professor of psychology and education at the University of London's Institute of Education, said he had found 'a very definite connection between class size and pupil attention in the very first year of school in the UK'. He said the effect of class size was quite significant. Smaller classes resulted in more interaction between teachers and students and a more effective learning environment. '[Learning] is more active in smaller classes and more passive in larger classes,' he said. In his research, Professor Blatchford looked at large-scale studies involving upwards of 20,000 British primary school pupils in a wide range of class sizes, analysing their performance in all subjects and using statistical analysis to take other factors into account. Professor Achilles has campaigned for smaller class sizes in the United States since the early 1980s. His research comparing students in classes of 13 to 17 with those in 'large' classes of 23 to 25 pupils during the past 24 years has often been cited by proponents of the policy. Lai Kwok-chan, head of the HKIEd's Centre for Research and Development of Small Class Teaching, said there was a huge difference between the situation in western and local schools. 'What Professor Achilles refers to as large classes are actually what most of us in East Asia would consider small classes,' Dr Lai said. The average size of a primary class in Hong Kong is 32 for those using activity-based learning and 37 for those using traditional methods. The academics' comments follow the release last week of a government paper for discussion at a meeting of Legco's education panel tomorrow. It suggested that research by the Education and Manpower Bureau at 37 pilot primary schools since 2004 had so far found little to support reducing class sizes. Chief Executive Donald Tsang Yam-kuen has made a gradual reduction in class sizes one of his re-election pledges.