CANBERRA, March 15 - Two reports released by the Australian Council for Educational Research (ACER) - TIMSS 2015: Reporting Australia's results and PISA 2015: Reporting Australia's results - find the gap between advantaged and disadvantaged students has barely narrowed over the past 15 years.

Education Minister Simon Birmingham, who is in the midst of negotiating a new school funding deal with the states and territories, said the warning signs in the results make it clear that money has to be spread around properly, based on need.

The analysis shows socio-economic factors, teachers and school environments make a big difference to student achievement.

The decline in the achievement of poorer students was especially worrying, ACER Director of Educational Monitoring and Research Dr Sue Thomson said.

"It also matters which school a student attends."

Her analysis found disadvantaged students in average schools were almost a year ahead in academic achievement compared with similar children in poorer schools.

And poorer students who attended advantaged schools were another year ahead again.

Disadvantaged students were less likely to describe most of their teachers as very engaging or supportive - but when they did find those excellent teachers they flourished.

Thomson also noted particular issues for Indigenous and non-metropolitan students.

"Substantially fewer Indigenous students achieve the TIMSS Intermediate international benchmark – the proficient standard for Australia – than their non-Indigenous peers.

"TIMSS also shows that students in provincial and remote schools are less likely to achieve the benchmark.

"We have seen no improvement in either case in 20 years of TIMSS testing and reporting," she said.

TIMSS 2015 assessed more than 580,000 students in Years 4 and 8 across the participating countries, including a nationally representative sample of around 16,000 Australian students from 572 schools.

PISA 2015 assessed more than half a million students across the participating countries and economies, including a nationally representative sample of around 14,500 Australian students from 750 schools.

The Australian assessments also found:

* One in five Year 4 students and one in 10 Year 8 students reported being bullied almost weekly - and did worse in school as a result.

* About one-third of students in richer schools and half those in poorer schools said most classes were noisy or disorderly and they found it difficult to learn.

* About two-thirds of maths teachers had trained in that subject.

* One in three principals of disadvantaged schools said inadequate infrastructure hindered their teaching capacity - compared with one in eight principals from advantaged schools.

The Australian Education Union highlighted findings that on every measure students at disadvantaged schools were more likely to be hurt by staff shortages, with the biggest issues in the Northern Territory, followed by Tasmania and Queensland.

Birmingham said Australia stacked up well compared with many countries but the warning signs were clear.

"This research demonstrates that more money spent within a school doesn't automatically buy you better discipline, engagement or ambition," he said.

"While well-resourced schools with highly capable and motivated teachers are central to success, we equally need policies and parents that empower teachers to expect high standards and adopt a zero tolerance approach to bad behaviour."

The two tests - TIMSS, assessing Year 4 and 8 maths and science, and PISA, examining 15-year-olds - were done in 2015. Their preliminary results were reported late last year.

Labor's education spokeswoman Tanya Plibersek said the results clearly showed poorer kids in poorer schools needed more help to catch up to their peers.

"Disadvantage is the biggest thing holding Australian schoolkids back," she said.

"We know the solution is giving the most extra support to the schools that need it."