More than 17 per cent of Australian year 9 students have failed to meet the national minimum standard in this year's NAPLAN tests and results have stagnated in other domains.
About 10 per cent of year 7 students, 7 per cent of year 5 students and 3 per cent of year 3 students are also falling short of the writing minimum standard, in a scenario that experts say is setting these pupils up for a "massive handicap in life".
"The minimum standard is so low it should be raised or scrapped, so if kids aren't even meeting that it's a real concern," the Grattan Institute's school education expert Peter Goss said.
"Once people fall behind, it's typically very hard to catch up, so someone at the cusp in year 7 is at risk of falling behind in year 9 unless they put the work in and get the right support."
Results have remained stagnant across most year groups for reading and numeracy, worsened for grammar and punctuation, and improved marginally for spelling.
"It's really frustrating if results continue to stagnate but we should think of education like a supertanker, it takes a huge amount of time and effort to change direction," Dr Goss said.
Federal Education Minister Dan Tehan said: "Today's results show that since testing began [in 2008], progress has been made in most areas, but there remains room to improve, particularly in the high school years."
The results come after widespread reports of issues during the online tests in May including lags, problems logging in and difficulties inputting answers.
David de Carvalho, head of the Australian Curriculum, Assessment and Reporting Authority (ACARA), which runs NAPLAN, said it will include a note with the results "that acknowledges the disruptions" but that the agency and an independent advisory group have "full confidence" that this year's results are comparable to other years.
About 50,000 students resat writing, reading, numeracy or language convention tests in a second round of testing due to the technical problems, and principals and teachers have raised concerns about the validity and comparability of the results.
Acting president of the Australian Education Union Meredith Peace said this year's NAPLAN data "is so seriously compromised it should not be relied upon by education departments, schools, parents and the broader community".
NAPLAN results have improved across most year groups for writing.Credit: Janie Barrett
"There is no transparency about how ACARA have arrived at the results data published today, and the community must seriously question just how rigorous the independent assessment of the NAPLAN results were," Ms Peace said.
President of the NSW Primary Principals' Association Phil Seymour said this year's tests are attempting to compare students who sat the tests on paper, those who did them online, those who had problems and were able to resit tests and those who had problems but were unable to resit.
"The results will throw it all out, they can't be compared to other years," Mr Seymour said.
He said the Primary Principals' Association will write to parents and teachers to express concerns about the latest results if the association is not satisfied with ACARA's communication.
Mr de Carvalho said about 37,000 students resat the writing test, 6500 the reading test, 3300 the numeracy test and 3500 resat language conventions.
Students resitting the writing test received a new prompt but those resitting the other exams did the same test that had been used in the original round of testing.
"It was a continuation of the tests [from where they had stopped due to technical issues], they weren't starting again," ACARA's general manager of assessment and reporting Peter Titmanis said.
"They might have had one or two questions they might have seen before [but because the online tests are adaptive] they might be directed to new questions."
A review of the problems during the online tests is under way and the full rollout of NAPLAN online has been pushed back from next year to 2021.
Mr de Carvalho welcomed the improvement in writing results and attributed them to targeted interventions by individual states and territories.
He said it is harder to improve results in other domains, where about 90 per cent or more of students are achieving at or above the national minimum standard.
Mr de Carvalho said ACARA has begun looking at introducing new "proficient standards" for NAPLAN tests, which will likely be harder to reach than the minimum standards.
The national minimum standard is set at band 2 for year 3 students, band 4 for year 5 students, band 5 for year 7 students and band 6 for year 9 students.