Booker Park School, based on Stoke Leys Close caters for students from Year One through to Year Six who have a range of complex learning difficulties.
In a report published just before Christmas inspectors raised concerns about a 'variable quality of teaching', 'inconsistent progress' by pupils and also said they felt the 'Booker Park curriculum is not yet fully developed.'
Inspectors say: "Pupils do not make consistently good progress in a broad enough range of subjects.
"Inconsistencies in the accuracy of teachers’ assessments of pupils’ learning mean that sometimes tasks are not matched to pupils’ needs closely enough, particularly in writing and maths.
"Most pupils achieve well in reading however pupils’ progress in other subjects, including writing and maths, is more variable."
Inspectors highlighted various strengths of the school saying pupils were safe and made good progress with their communication skills.
They said: "Pupils spiritual, moral, social and cultural development is a strength of the school.
"Pupils make good progress in their communication skills and rigorous safeguarding arrangements ensure that pupils are safe and well looked after."
The school was previously inspected in 2014 when Ofsted rated it as Good.
Responding to the report Booker Park School principal Christine Stephenson said: "As a school community, we are disappointed by the results of the Ofsted inspection report, however we are committed to acting on their recommendations to ensure significant and rapid improvements.
"The school had already identified many of the key areas to develop and therefore have taken action regarding these - as acknowledged in the report.
"Encouragingly, the Early Years provision of the school was judged to be ‘good’ and we are pleased that Ofsted has recognised the school’s rigorous safeguarding arrangements, the good progress pupils make in communication skills and that the fact that the pupils’ spiritual, moral, social and cultural development is a strength.
"We also welcome the positive feedback from parents and carers through ‘Parentview’.
"We feel that we are in a strong position to make the improvements needed and are confident that we will secure a rating of at least good at our next Ofsted inspection."