GCSE attainment gap is revealed
Twice as many pupils at the best schools in England got at least five good GCSEs last year than those at the worst, according to government data.
Nearly two thirds - 63.5% - of those at schools judged "outstanding" by school inspectors got five or more C grades at GCSE, including English and maths.
But just 31.7% attained this level among pupils at "inadequate" schools.
The Department of Education said it was "accelerating" its academy programme to bridge the "appalling" attainment gap.
The figures were provided in response to a parliamentary question, asked by Conservative MP for Burton and Uttoxeter, Andrew Griffiths.
Free school meals
Among pupils in schools judged to be "good" by the watchdog, Ofsted, just over half - 51.2% - gained five A* to C GCSEs, along with 43% of those in "satisfactory" schools.
The figures show the proportions of youngsters who attained five GCSEs - including English and maths, at grades A* to C - excluding equivalent qualifications, such as vocational awards.
Across England, 51.9% of teenagers achieved this benchmark last year.
The figures also show the proportion of pupils at schools rated as inadequate achieving five good GCSEs rises by 10.6 percentage points to 42.3% if equivalent qualifications are included, while in outstanding schools it rises 4.6 percentage points to 68.1%.
The parliamentary answer also indicates an attainment gap between disadvantaged pupils who attend outstanding and failing schools.
Eligibility for free school meals (FSM) is used as a key measure of poverty.
In 2011, just under two fifths - 38.9% - of FSM pupils who were taught at outstanding schools scored five GCSEs at grade C or higher, excluding equivalents.
Among FSM pupils at inadequate schools, just 14.3% reached this standard.
In schools rated good, 27.8% of FSM pupils got five or more A* to C grades. And, in those judged to be satisfactory, 23.9% achieved this level.
An Ofsted spokeswoman said: "All children have the right to a good education and that belief is at the heart of our work at Ofsted.
"The tougher, more stringent school inspection arrangements implemented from September 2012 raise expectations and focus on the importance of teaching to ensure all children get a good education.
"The short-notice inspections allow inspectors to see schools as they really are."
A Department for Education spokeswoman said: "This appalling attainment gap has been a feature of our education system for far too long. Too often the poorest families are left with the worst schools.
"That's why we are accelerating the sponsored academies programme, which has already turned around hundreds of under-performing schools across the country and is improving their results at five times the national average rate.
"We are also opening new free schools in some of the most deprived areas, offering parents more choice and higher standards, and targeting more funding than ever before at disadvantaged children through the pupil premium, which will double to £2.5 bn a year in 2014-15."
Academies and free schools are independent, state-funded schools, which receive their funding directly from central government, rather than through a local authority.
Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said the statistics should encourage people to "ask more probing questions".
He said the union had published research which showed that free school meals act as a "a broad and basic indicator, which doesn't account for issues like levels of deprivation, ethnicity, and per pupil funding", all of which had an impact.
Mr Lightman went on: "GCSE results only tell part of the story, and there will be good schools where results are not the highest, and weaker schools where there are high levels of raw attainment. Based on their entry, they are achieving.
"Schools are very concerned about the impact of their raw data on Ofsted inspections."