The scoring of GCSEs in England is set to change, as the government introduces a new number grading scale and more challenging content.

The new grades are being phased in starting with three subjects this summer, with most others expected to adopt the system by 2019, our sister paper The Mirror reports.

Once that happens, all GCSEs taken in England will receive numerical grades, but teachers say the switch is causing unnecessary confusion and will ultimately increase pressure on pupils.

Here is everything you need to know about the new GCSE grades and how they will impact your children.

What is the new grading system?

Pupils will be graded from 9-1 rather than A*-G, with 9 being the top grade and 1 the lowest.

The new scoring system will be used for English language, English literature and maths by current Year 11 students this summer as number grades are phased in.

That means students taking GCSEs in England will receive a mixture of number and letter grades when they receive their results , until the system is fully adopted.

Why is the scale being changed?

New grades are being introduced as part of a new curriculum that was introduced in 2014 and in a bid to drive up standards.

The government says new GCSE content will be more challenging and fewer grade 9s will be awarded than A*s.

Courses will be designed for two years of study and will no longer be divided into different modules.

Students will take all their exams in one period at the end of their course.

When will other subjects be phased in?

Another 20 subjects will have 9-1 grading in 2018, with most others following in 2019.

Those using the new system for the first time in 2018 include biology, chemistry and physics.

The final subjects to be phased in, in 2019, include psychology, business and media studies.

How do the new and old grading systems compare?

Under the new system a grade of 9, 8 or 7 would be broadly equivalent to an A* or A.

Grades 6, 5 and 4 are comparable to a B or C, while a 3 is similar to a D.

Grades 2 and 1 are comparable to E, F or G. The new system has kept U for ungraded.

Why are the reforms being criticised?

The NASUWT union says the reforms are creating "huge uncertainty" for schools and will heap more pressure on pupils.

It also fears the new scale will close some educational opportunities for students.

The union says there is confusion over grade boundaries.

Are GCSE scores changing anywhere else?

No, the changes are only happening in England.

Wales and Northern Ireland are not introducing the new 9-1 grading scale as part of their changes to GCSEs.

Scotland has its own exam system.