The teaching at Marshland St James Primary and Nursery School has been described as inconsistent by inspectors.
Following a two-day Ofsted visit in April, the school was given an overall grade of Requires Improvement.
The education watchdog said the school needs to improve the quality of teaching, learning and assessment.
In a report of key findings published on Tuesday, it said: “Teaching over time is inconsistent across different classes and subjects. Where practice is weak, pupils do not make sufficient progress.
“Teachers do not challenge the most able pupils sufficiently to enable them to achieve a greater depth in their learning.
“As a result, the proportion of pupils working above expected standards does not compare well with that of other pupils nationally.”
Pupils’ attainment in the last year’s key stage 1 and 2 national tests in reading, writing and maths was found to be below national average.
“In 2017, the most able pupils did not make sufficient progress in English and mathematics and therefore they did not reach the higher standards of which they were capable,” the report added.
However, the school, which has 90 pupils on roll, was praised for the “good progress” children make in Years 5 and 6.
Inspectors also praised the early years provision.
The report said: “The early years environment is stimulating and exciting for the children because of the vibrant displays and range of equipment available.
“Children really enjoy writing and they are given lots of opportunities to write in books, on the floor in the outdoor area and on the whiteboard.”
Inspectors noted described the pupils as “confident and happy” and said it was due to the “excellent care and guidance” they get from staff.
“They behave well and their conduct towards each other shows empathy and tolerance,” said the report.
Pupils’ behaviour was praised and inspectors noted they were well-mannered and polite.
The report continued: “Their movement and behaviour around school are calm and sensible. They show good table manners at lunchtime and make it a pleasant social occasion.”
In order to improve, inspectors say the school must equip teachers with the skills and knowledge to plan learning that enables most able pupils to achieve the standards of which they are capable, set higher expectations for achievement.”