Let us briefly remind ourselves of the current policy-context of this issue in Britain. The need to raise children's schooling attainments to a very substantial extent has become widely accepted in the past fifteen years following international comparisons (many based on research at this Institute) of workforce vocational qualifications and school-leaving standards. The consequences are expressed today in interventionist public policy in terms of a National Curriculum laid down for all school-ages (adopted ten years ago), together with more recent detailed syllabuses in the core subjects of language and mathematics embodied in the National Literacy and Numeracy Strategies for primary schools (adopted in the past two years). Much of the need for such reforms in Britain can be traced to worries as to whether teaching time was well spent, particularly in primary schools using ‘modern’ teaching methods which required children within each classroom to be divided into small groups, each group sitting around its own small table, many children not facing the wall-board (many classrooms even having their wall-board removed) so as to promote less ‘didactic’ teaching and more ‘discovery’ learning by pupils. The frequently ensuing difficulties of teachers in dividing their time effectively among those groups, the consequential frustration of those children who awaited the teacher's attention, the slower general pace of learning, and the particular disadvantages suffered by slower-developing children, need not be spelled out here; they have been closely examined in research involving timed classroom observation, such as the ‘Oracle’ project of Professor Maurice Galton and his colleagues.