Around 104 schools or "settings" across England are set to be disrupted - on top of 50 that have already been affected this year - over concerns about the building material Reinforced Autoclaved Aerated Concrete.
Schools minister Nick Gibb tells Sky News in most cases "just a few buildings" or rooms will have to shut but "in some cases it will be the whole school".
Many parents are still in the dark about whether their children will be able to return to classrooms at the beginning of the new term after the crisis dramatically escalated.