Ofsted plan to focus on children's individual progress under new inspection rules from September.
The new plans come after the watchdog concluded that teaching in some small private schools, where parents pay fees, was rarely better than 'competent'.
The Telegraph reports that Ofsted's annual report in November revealed that lessons were not good enough in a third of fee-paying schools it had inspected, and only seven per cent of teaching was regularly outstanding.
It will also examine how well children are prepared for life in a 'modern British multicultural society' after concerns were raised that some private faith schools may put pupils at the risk of indoctrination.
Ofsted's director of education and care Jean Humphrys told The Telegraph the quality of teaching is the key driver of school improvement: "One of the main findings from Ofsted inspection in this sector is that the quality of teaching in non-association independent schools tends to be competent but seldom inspiring. It is vital that our inspection is incisive and rigorous, and that judgements are fair, clear and helpful to a school's further development. With these new arrangements we will focus more sharply on what makes teaching truly effective."
Ofsted only inspects private schools if they are not members of the Independent Schools Council, and in total inspects just over 1,000 schools out of 2,400 in England.
Is your child at an independent school? What do you think of Ofsted's comments?