The Australian Curriculum, Assessment and Reporting Authority said because the ACT was such a high-performing territory, it was more difficult to point to above-average and substantial improvements in NAPLAN performance.

But for the first time, ACARA issued examples of government, independent and Catholic schools that, on the basis of last year's data, showed ''substantial gain from one NAPLAN test to another, for example, year 3 to year 5''.

ACARA stressed these were not the only schools in the ACT to improve by more than the average, nor did the list constitute a league table.

The schools included Arawang Primary, Jervis Bay, St John the Apostle, Burgmann Anglican, Turner Primary, Fadden Primary, Canberra Grammar, Torrens Primary, Aranda Primary, Richardson Primary and Trinity Christian schools, and Radford, Covenant and Daramalan colleges.

Several of these schools, including Burgmann, Radford and Canberra Grammar, were expected to produce the ACT's highest overall results, which The Canberra Times will collate later this week.

The Australian Education Union's ACT branch secretary Glenn Fowler said league tables were ''crude, unreliable and unnecessary''.

He said ACT students performed well by national and international measures and ''using raw data, such as NAPLAN or finance information, while adding to information about schools, is a narrow and incomplete way to assess a school's performance when taken in isolation''.

NAPLAN was introduced in 2008 to assess how well schools were teaching reading, writing and maths.

More than 9500 schools sit the NAPLAN tests in May each year across years 3, 5, 7 and 9. The My School website then provides yearly updates on how many students from each level perform at, above or below the national benchmarks.

It also has data on school finances, attendance levels and the socio-educational advantage of students.

ACARA chairman Barry McGaw said a feature this year would be a mapping function to allow parents to see their school's location in relation to other local schools.

ACARA had also changed the way it assessed the socio-economic advantage of student bodies - which ties in closely to results - following criticism of the way the Index of Community Socio-Educational Advantage (ICSEA) was calculated.

It previously used Bureau of Statistics census data but now uses information directly from parents about their educational backgrounds and employment.

''Over the last year, ACARA has worked closely with its partners and independent experts to make ICSEA school values more representative and stable over time,'' Professor McGaw said.

ICSEA scores indicate educational advantage before a school's impact on a student's results and is an important factor in comparing schools catering to similar and different student groups.

''Research shows that student educational outcomes are closely linked to family background factors, such as parent education level and occupation,'' Professor McGaw said.

''The value of ICSEA is that it enables fair comparisons to be made among schools with students from similar levels of socio-educational advantage.

''Differences among those schools are due to what the schools do and not the families from which the students come,'' he said.