The data discussed in this speech are taken from a large, three-year study that investigated the whole process of open-plan schooling. The study included a national survey of schools in Britain and a series of onsite observations. The analyses reported here derived from the observation of 552 pupils in grades 2 and 4 using the Pupil Behavior Schedule. The main areas of concern were curriculum allocation, which is the opportunity teachers provide for pupils to study a given curriculum content, and pupil involvement, which represents what pupils make of that opportunity. Large variations were found in the curriculum allocation between units. It is pointed out, however, that such variations are not limited to open-plan schools. The findings on pupil involvement can be interpreted in a number of ways. One might argue that pupils are involved for nearly two-thirds of the week, whereas another might complain that, on the basis of these figures, 9 of the 25 hours a week spent at school are devoted to noncurricular activities. It is of interest that some teachers manage to keep their pupils involved for 19 hours a week and others for only 13. (Author/IRT)