Modelling by the Grattan Institute found the gap widened by an extra 7 per cent over the two-month period that students were learning at home.

ACT students will be among the cohort to have lost the most because it had the second-longest official school shutdown period at eight weeks, behind Victoria's nine weeks.

The researchers recommend urgent action to help disadvantaged children catch up on their learning with a $1.25 billion strategy to implement small group tutoring and one-off catch-up funding for schools in lower socioeconomic areas.

Grattan Institute education fellow and report co-author Julie Sonnemann said it was likely all students learned at a slower rate but it was harder for disadvantaged students to catch up.

"Disadvantaged students, because they were already behind, this just compounds an already very difficult situation. So really that's why we're calling for a targeted strategy for disadvantaged students."

The researchers found disadvantaged students would have learned at about 50 per cent of their regular rate, meaning they would have lost about one month of learning in a two-month home learning period.

Those from lower socioeconomic area, rural and remote regions, indigenous backgrounds or who experienced mental ill-health already faced barriers to their learning.

During the pandemic disadvantaged students faced a lack of access to technology, home internet and a home environment that was conducive for home learning.

Ms Sonnemann said the remote schooling situation relied heavily on help from parents, support that research suggests disadvantaged students tend to have less of usually.

"It also relies heavily on being able to self-pace and get through the work at their own rate and we know disadvantaged kids tend to already be behind in their school work so that in itself is really hard to do."

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The researchers recommend governments should provide a national response for one million disadvantaged students, including a $1 billion investment in small-group tuition for struggling students.

They argue that recruiting university graduates and teaching assistants as tutors would have the added benefit of economic stimulus as young people were more likely to spend their income.

"I think sometimes governments need to bite the bullet and do the more expensive and intensive thing that works. It's more likely to work and it's much better use of money," Ms Sonnemann said.

The report recommends extra spending on literacy and numeracy programs for schools.

It also recommend allocating $95 million to evaluate the reform initiatives to identify what works in the hope of closing the existing educational gap.

"The existing poverty gap is over ten times bigger than any of the damage caused by COVID-19 and really that's the much bigger issue here.

"I think actually putting a spotlight on that and looking at the best ways to support teachers, that's what we can achieve with some of this stimulus money."