It is May, the month of bank holidays, royal weddings and – for 10- and 11-year-olds – Sats tests.

This week, around 600,000 Year 6 children will take tests in reading, maths and spelling, punctuation and grammar (Spag), the results of which will be used to judge how their schools are performing.

Two years ago, the tests were changed to reflect the new national curriculum: they were made tougher, which teachers were expecting, but the level of demand, the repeated clarifications on writing and two leaked papers meant the tests were condemned by unions and led to a review of the Standards and Testing Agency, an inquiry by the Commons education committee and a review of primary assessment by the government.

One of the changes from that review, more flexibility in how teachers assess writing, will be in place this year. But amid gathering protests from parents about the tests, and the stress they can create, the government has issued reminders to heads that they are legally obliged to ensure that pupils sit the Sats.

As we head into another stormy Sats week, here is everything you need to know about the key stage 2 national curriculum tests.

What tests do the children take?

Today, children in Year 6 will take a 45-minute Spag paper and be tested on 20 spellings.

Tomorrow there is a reading test, which consists of a booklet of three texts and an answer booklet. The test lasts for an hour.

On Wednesday, children take a 30–minute arithmetic test and a 40-minute maths reasoning test.

On Thursday, children take a further 40-minute maths reasoning test.

There is also a science test, which is taken by a sample of children every two years – this year the selected pupils will sit the tests between 4 June and 15 June.

Each pupil takes three science papers lasting no longer than 25 minutes each.

Do children have to do them?

The government has reminded headteachers recently that they have a statutory duty to ensure that all pupils in their school who are eligible and can sit the tests do so.

But, in truth, not all children do have to do them. Children should not sit the tests if they are working below the standard of the tests or are unable to participate.

And the details set out in the government's 58-page Assessment and Reporting Arrangements document, state that: “Headteachers make the final decision about whether it is appropriate for a pupil to take the tests. Some parents may ask a headteacher not to enter their child for the test. Parents may also ask a headteacher to enter their child for a test when the school has decided this is not appropriate. In all instances, the headteacher’s decision regarding participation is final.”

Last year, one headteacher used her discretion to refuse to enter any pupils for the Sats.

But all pupils at maintained schools and academies must be registered for the tests, including those who won’t take them. 

What about writing?

Teachers assess pupils’ writing against a set of national criteria. Children are judged as either working towards the expected standard, at the expected standard or in greater depth.

The criteria states that teachers’ judgements need to be based on a broad range of evidence which will come from day-to-day work in the classroom.

And local authorities visit at least 25 per cent of schools to check that teachers’ judgements are in line with others nationally.

And is that less controversial than the tested subjects?

No. This is perhaps the most controversial of all the Sats – and changes are being brought in this year after uproar over the new system.

The national criteria which teachers use to assess writing consist of a set of “pupil can” statements. For example, the pupil can: “use verb tenses consistently and correctly throughout their writing”.

When the new Sats were introduced in 2016, teachers were told that pupils had to achieve all of the statements within a standard to be graded at that standard, a method known as “secure fit”.

There was concern that this "secure fit" system was unfair and that the judgments were not consistent across the country. This year, changes have been introduced to allow more flexibility, with teachers being told that they can use their discretion to ensure that if a child has a particular weakness this does not prevent an accurate judgement being made of whether they have met the standard overall.

Are teachers happier now?

Not exactly. There is concern that the changes to the writing assessments are “as clear as mud”, and one Twitter poll conducted by Michael Tidd, headteacher of Medmerry Primary in West Sussex and a Tes columnist, found that four in five teachers felt that the new system would not produce “honest and accurate” results.

Why are these tests so important?

For many years, the Sats results have been used to judge schools’ performance. Schools that fell beneath set floor standards were at risk of forced academisation or a change of sponsor.

But that may be changing. Education secretary Damian Hinds, in his speech to the NAHT heads' union annual conference earlier this month, said that floor and coasting standards would be replaced with a single data trigger for schools to be offered support. And no school will be forced to academise based on data alone – only an "inadequate" Ofsted judgement will start such interventions.

And how did pupils do last year?

In 2017, 61 per cent of pupils reached the expected standard in reading, writing and maths – compared with 53 per cent in 2016.

There were 511 schools below the primary school floor standard in 2017, down from 665 in 2016.

When will pupils know their results?

Schools will get the results back at 7.30am on Tuesday 10 July. In previous years, the results have been released at midnight – resulting in late-night Twitter chats as headteachers around the country sat by their computers waiting for the results to drop.

Scripts are also returned to schools and checked by teachers – if schools want a paper reviewed, they must apply for this to be done by 20 July.

It is up to schools when they tell pupils their results. By law, they must tell parents before the end of the summer term and they must include the scaled score, a standardised score in which 100 is the pass mark, and whether or not a child met the "expected standard" – a wording which the Association of School and College Leaders condemned earlier this year as “harsh” and “damaging”.