Katharine Birbalsingh, 37, was ordered not to come into school on Thursday or Friday after making critical remarks before a speech by Education Secretary Michael Gove at the party conference in Birmingham on Tuesday.
Addressing the audience as a guest speaker, she gave a damning account of standards in schools, saying education had been "so dumbed down that even the children know it."
The board of governors at St Michael and All Angels Church of England Academy in Camberwell, south London, told Miss Birbalsingh to stay away from the school while they considered her position.
But the French teacher and deputy head has been told that she would be allowed to return to the classroom on Monday after parents voiced their support.
In her speech on Tuesday, Miss Birbalsingh told delegates of a "broken" system which "keeps poor children poor".
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