GCSEs in England have undergone sweeping changes as part of education reforms that began under the coalition government.

These changes are now being felt in schools and colleges across the country, with one of the biggest being a new grading system.

As teenagers prepare to receive their results this week, we explain the key change and what it means for students.

So, what is the new grading system?

– Traditional A* to G grades have been replaced with a 9 to 1 system, with 9 the highest mark.

– English and maths GCSEs – core subjects taken by all teenagers – were the first to move to the new system, with numerical grades awarded for these courses for the first time last summer.

– This summer another 20 subjects will have the new grades awarded for the first time, including core academic courses such as the sciences, history, geography and modern foreign languages.

– This change is only happening in England.

Why was the grading system changed?

– The move is part of a wider reform of exams which has seen a complete overhaul of the content and structure of GCSEs.

– Schools and colleges have been teaching these new GCSEs for the last two to three years, and it is only now that grades are starting to be awarded.

– The new courses feature much less coursework than the old GCSE qualifications, and modular courses, which saw pupils sit papers throughout their studies, have been scrapped in favour of “linear” GCSEs in which pupils take all of their exams at the end of the two-year course.

– The new grading system is meant to clearly distinguish new courses from the old qualifications.

What does this mean for students?

– This year, in the subjects that are being awarded new grades for the first time, it is expected that broadly the same proportion of students that would have got a C or above under the old system will get at least a 4.

– In general, a grade 7-9 is roughly equivalent to A-A* under the old system, while a grade 4 and above is roughly equivalent to a C and above.

– Fewer students will receive a grade 9 than would have received an A* under the old grading system. This is because part of the reason for introducing a new grading system was to allow more differentiation among the brightest students.

– According to one estimate by Cambridge Assessment, as few as 200 candidates could get a clean sweep of grade 9s across all of their GCSEs this year.

– It also means that this year, teenagers will get a mix of lettered and numbered grades, depending on the GCSEs they take.

Won’t this be confusing?

– There have been concerns raised that the system may be confusing, for example to parents, or businesses presented with potential job candidates with different types of grades.

– Different bodies, including England’s exams regulator Ofqual, have been publishing materials about the change and working to publicise the reforms.

What will this mean for pass rates and grade boundaries?

– There has been much talk about how grade boundaries could be lower this year under the new GCSEs compared with the old system.

– Grade boundaries are set by exam boards after marking has taken place in order to take account of how demanding the papers were.

– Last year, when grades were awarded for the first time for the new maths GCSE, students sitting the higher tier maths GCSE exam, which is aimed at higher-achieving pupils, needed to score at least 18% on average to secure a grade 4, while 52% was the boundary for a 7 on average, and 79% was the average required for a grade 9.

– Some people raised concerns at the time that these boundaries were lower than under the old system, and there have been similar suggestions recently that the same thing will happen this year as more new GCSEs are awarded for the first time.

– Ofqual has said that it uses statistical processes to ensure that results are comparable year-on-year, and to ensure that students who are the first to take the new-style qualifications are not disadvantaged in any way.

How have we got to this stage?

– Education reforms in England began in 2011, led by then-education secretary Michael Gove. A review of the national curriculum was announced first, with the overhaul of GCSEs starting in 2013.

– In 2014, Mr Gove said the new tougher GCSE courses “set higher expectations”, adding “they demand more from all students and specifically provide further challenge to those aiming to achieve top grades”.