Australia's children are reading and writing better than a decade ago but there still needs to be a strong focus on the basics, particularly in high school.
The final 2018 NAPLAN results are released on Monday, confirming the findings in the preliminary report last August.
It shows there have been significant gains across some domains and year levels since the national literacy and numeracy testing began in 2008.
However, the rate of growth is a lot slower for Year 7 and 9 students than at the primary school levels, says the head of the body that oversees the tests, Australian Curriculum and Assessment Reporting Authority's David de Carvalho.
This mirrors a worldwide phenomenon, and could reflect the fact literacy and numeracy are taught less explicitly in the later years of school.
As well, there is a general trend of student engagement dropping off as they reach high school.
"This is a challenge, I think, for all of us involved in education to think about how we can keep focus, keep young people engaged in their education right through to the end of Year 12," Mr de Carvalho told reporters ahead of the report's release.
"I think it's particularly important that the focus on literacy and numeracy not be lost in the secondary schools."
The results show a positive story for indigenous students, who are progressing faster than the general population.
Mr de Carvalho said this shows there is a lot of good work being done by indigenous students, their families and communities, supported by teachers and targeted investment.
"However, even though these high rates of growth are something to take comfort in, it's still going to take too long to effectively close the gap in literacy and numeracy," he said.
"If these rates of growth were to continue, we wouldn't see a closing of the literacy gap until some time in the next century."
Education Minister Dan Tehan said there had been real improvements across the board in spelling, grammar and punctuation since testing started, but there was still more work to be done in the writing area.
"But it does show that we are seeing real improvements from the record investment the government is putting into education," he told reporters in Canberra.
