Supersession classes could become the new norm, they fear, as new figures show, that the population of the secondary school will swell to 3.3 million within a decade.
TThe hike is fueled by a baby boom in the early 2000s and a high birth rate among women from immigrant communities.
The excesses in the child population have found their way through the school system and have passed from primary school to secondary school.
Over the next ten years, student numbers are expected to increase by 14.7 percent, with another 418,000 children expected to attend secondary schools by 2027, according to the Department of Education (DfE) recent projections.
The official forecast will trigger new worries about the increased class sizes and the school shortage.