By Sean Coughlan
BBC News education correspondent, Birmingham
David Laws promises extra spending in a pupil premium
Separate school league tables for schools serving children from rich and poor backgrounds, have been called for by the Liberal Democrats.
The idea could mean performance tables delivered in football-style leagues at different levels, rather than making national comparisons.
Schools spokesman David Laws told the NASUWT conference there should be a fairer way of measuring schools.
The current system penalises schools working in tough areas, he said.
Mr Laws said that it was impossible to stop exam league tables being published, but they should be delivered in a way that allowed more revealing comparisons.
"We want to be able to compare schools in a meaningful way. At present, it just tells you about the catchment area," he said.
It was more relevant to compare local schools with those in other parts of the country serving similar areas, he argued.
This would mean grouping together schools according to factors such as the number of pupils on free school meals, ethnic minority and migrant children.
He said that, particularly in London, there were schools serving disadvantaged areas that were outperforming schools in leafier suburbs - but under his plans such schools would appear in separate levels of league tables.
Such successful inner-city schools would no longer appear as high performers in national rankings, measured against national standards - but would appear in a league table for deprived areas.
Mr Laws rejected the idea that this would be labelling schools according to the background of their pupils or restricting their ambition.
Instead he argued it would provide more relevant information.
"We need to find a way to reward the efforts of schools working with some difficult groups of young people," he said.
And he drew a comparison with police performance data, which he said would not try to draw conclusions from comparing crime figures in the inner city and an affluent suburb.
With the general election approaching, Mr Laws also criticised the Labour and Conservative versions of the pupil premium policy, which is intended to target extra funds at poorer pupils.
Mr Laws said that about a million pupils would benefit from his party's pupil premium policy, which would cost about £2.5bn - to be funded by £1.5bn cuts outside education and £1bn saved from non-schools spending within the education department.
He accused the Conservatives of promising a pupil premium system that was "non viable" without extra funding - and said that there was not a "hope in hell" that it could work if it depended on taking money from other schools' budgets.
And he said that Labour's version of pupil premium was just a "repackaging exercise", using existing deprivation funds.
In terms of what distinguished his party's education policy, Mr Laws said he could promise the guarantee of extra funding for schools and the pupils who needed the most support.