Teachers spend on average just 16 hours of a 35-hour working week teaching, according to a survey by the Human Sciences Research Council. This is far short of the 64 to 79 per cent of working hours they are supposed to teach.

The study, Educator Workload in South Africa, surveying nearly 4,000 teachers from 900 schools, found teaching is being muscled out by management, assessments and formal and informal extra-curricular activities.

The problem is most severe in rural schools and former “coloured”, Asian and especially African secondary schools. In some schools, staff spend just 10 per cent of their time in class.

Yet three in four teachers said that their workloads had increased hugely since 2000, resulting in more stress. They also complained of lack of resources, oversized classes - the larger the class, the less time teachers spend in them - and a growing burden of state requirements.

The study was commissioned by the Education Labour Relations Council. Its secretary-general Dhaya Govender expressed concern at low morale and high absenteeism among teachers, which he blamed among other things on illness, and declining pay and conditions.

Other recent teacher surveys have revealed major problems among the 350,000 teachers. One reported that 13 per cent were infected by HIV; another that 11 per cent had been hospitalised and three-quarters had sought medical help in the previous year; and yet another revealed that more than half were considering leaving the job because of stress and workloads. Violence in schools was also a worry.

The study recommends protecting teaching time, reducing class sizes, improving administrative support at schools and reducing the number of learning areas in the curriculum - especially in areas where there are few trained teachers.