A teachers' strike could force Furze Platt Secondary School to close for the day.
Headteacher Tanya White wrote to parents after the National Union of Teachers (NUT) announced it will stage its next strike on Thursday.
She states that is not clear how many teachers will be participating in the action but that either "partial or full closure of the school is possible."
Parents have been advised to make provisional child care arrangements.
The last NUT strike was staged in March over changes to pay, pensions and working hours.
Most schools remained fully open, but Altwood School, Cox Green School, Furze Platt Senior School and Newlands Girls' School were only partially open for some years and classes.
Furze Platt Junior School and Holyport Primary School were also partially open.
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