Here is the Abstract:

It is now recognised by many that we need to know more about effects of class size on classroom interactions and pupil behaviour. This paper extends research in several ways:
a. it compares effects on two main types of behaviours – pupil classroom engagement and teacher to pupil interaction
b. it examines if effects vary by pupil attainment level
c. it examines effects of class size on classroom processes across the whole of the primary and secondary school years
d. it studies effects across the full range of class sizes found in UK schools
e. it uses systematic observation data to capture effects of class size on moment by moment behaviours and employs sophisticated multilevel statistical analyses that controls for possibly confounding factors and deals with the clustered nature of observation data within pupils and within classrooms within schools.

Results showed that as class sizes became smaller there were more times when pupils were the focus of a teacher’s attention, and more times when they were engaged in active interaction with teachers. This effect was found for all groups at both primary and secondary levels. It was also found that pupils’ classroom engagement decreased in larger classes and this problem was particularly marked for the pupils who are already attaining at lower levels. This, in turn, was accompanied by teachers seeking to control low attainers more than other groups in larger classes. It was suggested that small classes can be a valuable educational initiative right through school, but could be particularly targeted at lower attaining pupils at secondary level.