One in three teachers have seen temperatures soar to more than 31C during the period of a survey carried out for the National Association of Schoolmasters Union of Women Teachers.
Three quarters of teachers surveyed reported that temperatures rose to at least 24C on a quarter of the days during the survey period. The NASUWT, which published the survey at its annual conference in Birmingham, is campaigning for a legal maximum temperature for classrooms.
It says action should be taken to lower the temperature if it is higher than 24C and teachers and pupils should have the right to walk out if it is more than 30C.
According to the survey, nearly half the teachers believed pupils’ ability to concentrate was impaired once the temperature went beyond 24C and half said their ability to teach was also affected. At 30C, 82 per cent said pupils’ ability to learn was "considerably adversely affected".