"It does not seem too bad when we say 91.8 per cent of Western Australia's year 3 students achieved or exceeded the national benchmark for reading or 92.3 per cent exceeded the benchmark for spelling," the new MP for Perth wrote in an opinion piece published in The West Australian newspaper this weekend.

"That is until one learns what the national benchmarks are.

"To meet the 2013 national benchmark for reading, a year 3 student has to only answer eight out of 36 questions correctly. To meet the standard for spelling, only three correct words out of 25 words are required. In 2011, one correct answer out of 25 was enough to get a student across the line."

But Rob Randall, chief executive of the national testing authority ACARA, said Ms MacTiernan was confusing benchmark descriptions of children's abilities with the minimum standards.

"While we appreciate the focus on standards, we would note that Ms MacTiernan confuses the notion of benchmarks or standards with the notion of how many items you need to get right to be placed in each of these bands."

Children's NAPLAN test results are divided into 10 "bands", which rank children into achievement levels.

"Only a few items are needed to judge whether a student is at the minimum standard," Mr Randall said.

"Other items in the test are used to tell how far beyond the minimum standard each student is at."

For example, if a child spelt only three words correctly in an English NAPLAN test, checking which words were spelt correctly would help markers identify children's strengths and weaknesses.

Ms MacTiernan, however, argues Australia needs to return to a "back to basics" approach to teaching, for example "explicit, highly-structured teaching of sounds, syllables and grammar".

"There have now been major investigations into the teaching of reading and writing by Australian, UK and US governments," she wrote.

"Each found unequivocally that this method of explicit, highly structured teaching of sounds, syllables and grammar is the most effective method of teaching fundamental literacy to all.

"For some reason in Australia, our educational leaders will not act on this."