The union rolled in to Canberra yesterday, parking its ''schools campaign bus'' on the lawns of Parliament House, and calling for a huge injection of government funding to public schools.

The union's campaign comes on the eve of release of the review led by David Gonski into schools' funding, and the government's response to the report, due on Monday.

Fairfax understands the government will issue only an ''initial'' response to the report, and will announce on Monday it will go through another consultation process with stakeholders.

But union federal president Angelo Gavrielatos said it was incumbent on the government to act quickly on the report's findings.

''The government commissioned this review, the government hand picked this panel and it goes to their credibility,''he said.

''It goes to the credibility of the government, the next steps they take, and what we say to the government very clearly is, resources delayed are resources denied.''

Yesterday, the Grattan Institute released a report that showed school expenditure levels are no guarantee of good student results, nor do smaller class sizes guarantee good educational outcomes. Between 2000 and 2008, average expenditure per student rose by 34 per cent across the OECD, and 44 per cent in Australia.

But by 2009, Australian students' performance had fallen by the equivalent of three months compared with 2000 results.

Mr Gavrielatos rejected the report.

''You know, any parent, and any teacher will tell you there is a clear link [between funding and results].

''If there weren't a clear link, why is it that private schools continue to market themselves on their small class sizes and the like, courtesy of government funding that is funding a resource gap between government schools and private schools?''

Greens leader Bob Brown said nothing less than a multi-billion dollar investment was needed.

''All Australians have to understand that we are at a historic moment, this is a 40-year review that's been awaited into education, which is fundamental to any community and every child in our country and we're talking now about setting the template for the next half century or century,'' he said.

''So this is critically important, and key to this is bringing up Australian funding to the equivalent of other similar countries around the world. We're right up the back … And we need to catch up and that is a multi-billion catch-up. And the question to both the major parties is, 'will you allocate that money in the coming budget'.''