New provisional results show GCSE performance has fallen at most schools in Mansfield and Ashfield.
But this week head teachers moved to reassure parents that schools are not underperforming and say the tables are misleading.
The provisional figures have been published by the Department for Education (DfE) to enable parents to make an informed choice for secondary school applications.
School chiefs say because the results only included first entries and not resits they paint a worse picture than the full secondary performance tables which will be released in January 2016.
It is the first time provisional figures have been released before they are finalised .
The tables for percentage of pupils achieving 5+A*-C GCSE (or equivalent) including English and maths show a decline of more than 10 per cent for some secondary schools.
At Nottinghamshire County Council, John Slater, Service Director for Education Standards and Inclusion, said: “GCSE results this year show a variation across schools in the county and there is a concern that some of the schools are significantly underperforming.
“Most of these schools are academies and not under the control of Nottinghamshire County Council but we are always keen to work closely with academy providers and sponsors to get the best possible education outcomes for our young people.
“In the next few weeks we will be writing to schools, including some schools in Mansfield, seeking reassurances as to the actions that are being put in place to improve results.”
Joseph Whitaker School, Samworth Church academy and Ashfield Comprehensive School saw their results rise by three per cent, two per cent and two per cent respectively.
Garibaldi College and Queen Elizabeth’s Academy showed the largest falls with -12 per cent and -10 per cent respectively.
Joseph Whitaker School head David Bell said the school considered the league table to be ‘misleading’. He said: “Examination outcomes at Joseph Whitaker School in 2015 were 66 per cent in 5+A* - C grades including English and Maths. The figure of 50 per cent quoted in the DfE stats is the first entry figure. We are delighted with the outcomes for the students and teachers who have achieved this. They have worked extremely hard.”
Mansield’s Samworth Church Academy Principal Barry Found, said: “When you look at the three-year trend we are the only school in Mansfield which has improved year on year.
“All other schools have declined unfortunately.
“There have been a number of quite difficult issues with the English exam grade and the boundaries for higher maths have been raised considerably.
“I think raising the bar is never a bad thing.
“It is about making students wanting to be better and better prepared.”
Garibaldi College Head Ryan Hawley said the provisional performance tables can be misleading for parents because they only compare attainment of students and don’t take prior ability into account.
He added: “The figures this year are misleading for Garibaldi students because they only included the first entry results for our students, which was 46 per cent.
“Our curriculum is structured to ensure that every student does as well as they possibly can.
“This sometimes involves students having to do a re-sit to improve a grade in a subject, the problem with the performance tables are that they do not show this re-sit result.
“Next year performance tables are changing and the new Progress 8 measure will be fairer for all schools.”
Warsop’s Meden School showed a fall of 6 per cent this year Head of School Janet Brayshaw told Chad: “The results are provisional and following resits the figure has gone up from 48 to 50 per cent.
“This final figure exceeds our targets based on prior attainment. That puts us in the top 25 per cent of schools nationally.
“On the surface it appears to be a drop but it isn’t in terms of students making progress.
“The resit marks achieved are what they take with them and the actual figure was 59 per cent. At the end of the day that is the most important thing.”
At Quarrydale School, Sutton the tables show a fall of three per cent from 57 per cent to 54 per cent.
Head Jonathan Crone said the fall was not significant. He said; “Generally we are still quite happy.
“The national average has dropped by nearly one per cent at 52.8 per cent and we are still above that.
“We believe our re-marks will bring us broadly in line with last year.”
DfE provisional tables percentage of pupils achieving 5+A*-C GCSE (or equivalent) including English and maths.
Samworth Church Academy: 2013 - 52 per cent, 2014 - 51 per cent, 2015 - 53 per cent.
The Brunts Academy: 2013 - 68 per cent, 2014-57 per cent, 2015 -53 per cent.
Queen Elizabeth’s Academy; 2013 34 per cent, 2014 - 39 per cent, 2015 29 per cent.
The Manor Academy: 2013 - 57 per cent, 2014 - 40 per cent, 2015 - 39 per cent.
Garabaldi College: 2013 - 67 per cent, 2014 - 68 per cent, 2015 - 46 per cent.
Joseph Whitaker School: 2013 - 73 per cent, 2014 - 47 per cent, 2015 - 50 per cent.
Quarrydale School: 2013 - 71 per cent, 2014 - 57 per cent, 2015 - 54 per cent.
Sutton Community Academy: 2013 - 0 per cent, 2014 - 46 per cent, 2015 - 46 per cent.
Meden School: 2013 - 59 per cent, 2014- 54 per cent, 2015 - 48 per cent.
Kirkby College: 2013 - 53 per cent, 2014 - 29 per cent, 2015 26 per cent.
Ashfield Comprehensive School: 2013 - 58 per cent, 2014: 51 per cent, 2015 - 53 per cent.