Parents should ignore this year’s primary school league table results, as drastic changes to the curriculum mean test scores are an unreliable assessment of schools’ performance, the BBC reports.

New, tougher end of primary SAT exams meant that only 53 percent of children passed them, compared to an 80 percent pass rate on the old SAT last year.

Russell Hobby, general secretary of the National Association of Head teachers (NAHT) has said that ministers themselves have stressed that due to these changes, parents cannot rely on the league table results to assess schools performance, as this would be an unfair comparison.

Pupils at nearly 14,930 state primary schools in England sat the new SATS, which assess children in reading, writing and maths- known as the three Rs. Children also sat a grammar and spelling test.

School rankings are then produced by the government, helping parents to make informed choices on what school to send their child to, or judge the performance of the school their child attends.

In the lead up to and during the tests, teachers and heads across England complained that the new papers had been set at too high a level and that not enough information had been made available.

The government had set its expectation that 65% of pupils in each school should meet the new expected standard in the “Three Rs”. About 11,000 schools failed to meet this target.

However, the Department for Education (DfE) said schools that achieved sufficient progress scores in reading, writing and maths would not be considered to be failing.

The Dfe had deliberately held steady the percentage of schools deemed to be failing at 5% – the same as last year – so that the volatility of this year’s results did not lead schools that were otherwise successful to be targeted for intervention.

Only 47 schools reported that all their pupils had reached the expected standards in the new SAT.

General secretary of the National Association of Head Teachers, Mr Hobby, said:

“The pass mark for the test was set at a ridiculously high level. We have just failed half the children in the country and yet Ofsted is saying nearly 90% of schools are good or outstanding.

Pupils were doing what they should have been doing in the early years of secondary school. Some of the grammatical stuff was the same level as GCSE English.”