Croft Academy sent a letter to parents on Monday about the confirmed case.
The letter says: "We have been advised by Public Health England that there has been a confirmed case of Covid-19 within the school.
More Covid-19 coverage:
"We have followed the national guidance and have identified that your child has been in close contact with the affected child.
"In line with the national guidance we recommend that your child now stay at home and self-isolate until September 29 - as this will be 14 days since the child was in school.
"We are asking you to do this to reduce the further spread of Covid-19 to others in the community.
"If your child is well at the end of the 14 days period of self-isolation, then they can return to usual activities."