Young children are spending the Easter holidays in Sats revision classes at hundreds of primary schools, a union has said.

The last five years have seen a growing trend in the number of schools opening over the break for “cramming” sessions ahead of the tests in May, according to Darren Northcott, NASUWT’s national official for education.

He said it was partly down to the pressure schools feel under the accountability regime.

While attending, and running, the classes is voluntary, it is not known what messages schools are sending to parents about them.

But he added: “Where is the evidence that spending time over the Easter period – effectively cramming for a Sat – is going to make the result any better than it would otherwise be?”

“It seems like an ill-conceived response to this pressure,” said Mr Northcott at the union’s annual conference in Belfast.

He also said it was likely that once one school in an area decided to hold the classes, others felt they had to follow suit in order to achieve certain standards.

When asked whether the Key Stage 2 revision sessions stopped children from having balanced lives and playing, Mr Northcott said “absolutely”.

He continued: “When you ask children, their viewpoint would be that their time might be better spent playing, or relaxing.”

Mr Northcott added: “ If they have been set homework and if that homework is useful and productive they should be doing that – but they also should be doing enjoyable , engaging things in their own time, with their own friends, spending time with their families which is all a critical part of a healthy childhood.”

Speaking about why primaries are opening up over Easter, Mr Northcott said: “Schools think that this is going to give them an edge in getting the results they need – so that’s the driver.

“That’s what lies at the heart of it, that’s the perception.”

The trend seems to be most popular with the schools concerned about how they sit in the various performance measures, and those aware that they are close to or below the coasting or floor standards, the former teacher explained.

Posts on Twitter appeared to show year six pupils sitting in classrooms over the holidays.

In one the children had been rewarded for their hard work with a Happy Meal, while in another they wore Easter hats as they got stuck into the books.

Last week Labour leader Jeremy Corbyn announced Labour would scrap Sats if they came into power.

Shadow education secretary Angela Rayner said: “This is just the latest example of the impact that the current Sats regime is having on children, teachers and schools.

“Our pupils are the most tested in the world, but there is no evidence that the current high-stakes testing regime improves teaching and learning.

“Replacing the current system will reduce the burden of testing on children and teachers, encourage a broad curriculum and separate the assessment of schools from the assessment of children as young as seven”.