Headteachers' leaders have said that the use of a rota system to bring back secondary students in September is "the most likely scenario".
Geoff Barton, general secretary of the Association of School and College Leaders, told Tes that he thought it unlikely that all secondary students would return in September, and that a rota system of different groups of pupils attending from one week to the next was most probable.
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Last night a senior minister said that secondary schools would not open "until September at the earliest". And today education secretary Gavin Williamson said he wanted all pupils back in school in September.
Mr Barton said: "Scenario one is all children will be able to go back in September – that will depend on the way the virus spreads or doesn’t spread.
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"But we would be advising schools to have a think about that, so if you’re going to have all your children back in secondary, what do you do with them, what does the curriculum look like, etc?
"But I think, realistically, if it’s the case that social distancing continues to apply, then you’re not going to have all the children back, because they have to be kept separate on the buses in the community.
"So that leads to scenario two, where some children are in school and that’s where rotas are definitely part of the thinking."
The government's Scientific Advisory Group for Emergencies (Sage) has previously said that half-class rotas are the safest way of keeping the R rate – the rate of transmission – down.
Mr Barton said that the rotas would be on an all-day basis, with schools with two-week timetables bringing in half of one year group for two weeks followed by the other half.
"It’s not 'let’s bring half the year group in the morning and half in the afternoon'," he said.
He said schools needed to consider which parts of the curriculum would need to be taught within school where teachers could assess pupils' understanding, and which could be carried out at home as consolidation work, which was not possible currently when teachers were not seeing pupils.
"That’s where blended learning becomes more blended, in theory at least, because the teacher can manage what it is the child’s doing at home. So, personally, I think that’s the most likely scenario," he said.
Mr Barton said rotas would be "more problematic" for primary pupils, who might struggle with independent learning or need more consistency. But in both primary and secondary decisions would depend on public health guidance at the time, which would, in turn, depend on the rate of transmission.