Some children will not be returning to school next week, it has been announced - due to the new strain of coronavirus.
Education secretary Gavin Williamson told the House of Commons that the government had to "act swiftly" and make "immediate adjustment to our plans for the new term", in light of soaring coronavirus infection rates.
All pupils in year groups studying for exams will return during the week beginning January 11, instead of next week.
There won't be a full return of all students until January 18, but schools will still be open from January 4 for the children of key workers.
Mr Williamson also said some primary schools in the highest risk areas would also not return next week.
Some primary schools in Essex are closing but all in Suffolk are due to open as planned.
The delays are designed to allow schools to get ready for mass testing of pupils and staff with symptoms, with 1,500 military personnel on hand to provide virtual training.
However, former Suffolk headteacher Geoff Barton said teachers would be "frustrated" at the last-minute nature of the government's announcement.
Mr Barton, previously headteacher of King Edward VI School in Bury St Edmunds and now general secretary of the Association of School and College Leaders, called the decision to delay the return "unsurprising" but cited concerns about the logistical challenge of mass testing.
He said: "Schools and colleges will be frustrated that the new arrangements for the spring term have once again been communicated late and after days of speculation.
“We appreciate this is a fast-developing situation but the government has made a habit of chaotic 11th-hour announcements which leave schools and colleges picking up the pieces.”
Dave Lee-Allan, chairman of the Suffolk Association of Secondary Headteachers, said he felt "anger and disbelief" when the government announced the planned testing as schools broke up for the holidays, leaving no time for preparation.
He doubts the virtual training from the military will be of much practical use and said space to complete tests was another issue being faced by schools.
Graham White, Suffolk representative for the National Education Union, called for all schools to close to allow time for testing.
He too is concerned about the burden being placed on schools to complete the testing, with very little training and remote help from the military.
Councillor Jack Abbott, Labour's spokesperson for children's services, education and skills at Suffolk County Council, criticised the government's handling of the situation.
He said: "We just are a matter of days away from the start of the new school term with schools and families desperately needing clarity, yet Gavin Williamson made a complete mess of his long overdue announcement and left people with more questions than answers."
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