The number of pupils in a class or school divided by the number of teachers. In a maintained primary school the number of teachers employed will be based largely on the number of pupils on the school roll, so that if the number of enrolments falls, teaching posts may be lost rather than class sizes reduced. In secondary schools the situation is rather more complicated, as specialist teachers must be employed to cover each curriculum subject. A pupil–teacher ratio which creates class sizes of more than 30 pupils will normally raise concerns from parents and teachers, as it is widely believed that pupils will benefit more from being part of a smaller group in which the teacher is able to give more attention to each individual. For example, in independent schools the pupil–teacher ratio is normally significantly lower than in the maintained sector. However, the relationship between pupil–teacher ratios and the effectiveness of teaching must also take into account the nature of the learning activities. The effectiveness of a teacher‐centred method such as exposition or lecture may be very little affected by class size, while learner‐centred activities such as discussion or discovery learning may work much better in group sizes which allow the teacher to give individual attention where it is needed. By the same principle, the pupil–teacher ratio will have an impact on the range of learning activities which the teacher is able to facilitate effectively.