Victoria is leading a push for an overhaul of the NAPLAN school testing system, proposing a job certificate to help engage students and a change to the ages of test-takers, to combat flagging results in high schools.

Key points: The results show there has been little improvement in test scores across the board

The results show there has been little improvement in test scores across the board Year 9 students were the "most difficult" to engage, according to the Victorian Education Minister

Year 9 students were the "most difficult" to engage, according to the Victorian Education Minister Victoria, NSW and Queensland are running an independent review into NAPLAN

National preliminary figures for the 2019 tests showed while primary school students had small lifts in average scores in some areas, results were stagnant for most categories.

Nationally, Year 7 and 9 students slid backwards on the baseline score in writing and Year 9 students' scores were flat across the board.

The results, released this morning, are further ammunition for critics of the assessment scheme, with three states, including Victoria, already leading a review into the tests.

Federal Education Minister Dan Tehan conceded there was "further work to do" in bringing up literacy and numeracy scores.

Victorian Education Minister James Merlino said Year 9 was "the most difficult" cohort to engage in their education.

"If they don't see the relevance in the test, they're not going to take it seriously," he said.

In a bid to boost engagement, he has proposed linking the tests to a literacy and numeracy certificate for Year 9 students to show would-be employers.

The results showed a slump in literacy and numeracy results for high school students. ( ABC News: Nicole Chettle )

"We need our Year 9 students to think 'OK, this test means something, I'm going to give it my best shot, and I'm going to give it my best shot because I'm going to get a certificate that's going to go into my careers portfolio'," he said.

A newly-established advisory committee of principals from government, independent and Catholic schools will begin assessing the proposal.

States urged to review ages of NAPLAN students

The National Assessment Program — Literacy and Numeracy, better known as NAPLAN, is standardised testing taken by students in years 3, 5, 7 and 9 across the country.

The tests have proved controversial, particularly their move from pen and paper to online, which has seen widespread computer glitches affecting students and concern over the legitimacy of the results.

The three largest states — New South Wales, Queensland and Victoria — are running a review of the system, which has been operating in its current form for more than a decade.

The tests have been undergoing a shift to online. ( ABC News: Natasha Robinson )

Mr Merlino said he had asked the review to consider changing the target students to those in years 4, 6, 8 and 10.

"It makes common sense to me," he said.

Any recommendations made by the states' review would need to be accepted by the Australian Curriculum, Assessment and Reporting Authority (ACARA).

'Let's not blame the tests,' Tehan urges

Mr Tehan said he wanted to work with states and territories to make sure they kept "their eye on the ball" to improve secondary school results.

His Opposition counterpart Tanya Plibersek said the Government had shown a "a complete failure to address the problems in our schools".

"Of course the Federal Government has a responsibility here," she said.

The Australian Education Union (AEU) seized on the results to renew its criticism of online NAPLAN testing, which it said was plagued by issues that "fundamentally undermine the credibility of the data".

"Despite whatever story ACARA tries to spin, this data is so seriously compromised it should not be relied upon by education departments, schools, parents, and the broader community," AEU acting federal president Meredith Peace said.

"Teachers and principals cannot trust NAPLAN or the results it has produced."

Meredith Peace cast doubt on the validity of the data. ( Supplied )

Mr Tehan defended the system and said Australians would not know about problem areas without them.

"Let's not blame the tests. Let's make sure that we understand what the results are and where we need to put the work in," he said.

ACARA CEO David Carvalho said the results were reviewed by independent measurement advisory experts before their release and results should be interpreted "with care".

Despite the flagging results for Year 9 students, Victoria's primary schools led the country in seven out of 10 different measures.

Across the country, there was an upturn in all student writing results compared to 2018.

"NAPLAN results for 2019 in writing have shown a pleasing improvement from last year, and it is a trend we would like to see continue, given the decline in recent years across all year levels," Mr Carvalho said.

Students and schools will receive their individual results next week.