The latest literacy and numeracy test results show most Canberra students perform well above the standards of other Australian children.
But the ACT's results remain poor when compared with students interstate of similarly wealthy and educated backgrounds.
The My School website, which rates individual schools' performances, was updated this week with last year's testing outcomes.
Students in years 3, 5, 7 and 9 are assessed in reading, writing, spelling, grammar and numeracy.
Canberra's average results were among the nation's highest in every area and year, except for year 3 writing, where the Victorian average was higher.
In recent years, the Australian Curriculum, Assessment and Reporting Authority, which manages the so-called "NAPLAN" tests, has encouraged parents to focus not on raw scores but on how, over the course of two years, schools improve the skills of the same group of students.
In the ACT, three public schools in particular – Charnwood-Dunlop in west Belconnen, Taylor Primary in Kambah, and Maribyrnong Primary in Kaleen – had stunning successes across the board in boosting the results of 2017's year 5 pupils, compared with when they were in year 3.
In high schools, the overall gains for last year's year 9 students were highest at Catholic girls school Merici College, and three public schools: Caroline Chisholm in Tuggeranong, Melrose High in Woden, and Melba Copland Secondary in Belconnen.
The latest raw scores show that public schools with children from particularly wealthy backgrounds, such as Turner, and the elite private schools – Canberra Girls Grammar, Canberra Grammar and Radford College – perform best in literacy and numeracy.
In a report last year, the ACT's public sector watchdog, Auditor-General Maxine Cooper, strongly criticised the Education Directorate's failures to use the NAPLAN data more effectively to target underperformance.
"ACT public schools are performing below similar schools in other jurisdictions despite expenditure on a per student basis for public schools being one of the highest in the country," she wrote.
Dr Cooper said reviews of government schools had "consistently identified shortcomings in their analysis of student performance information and their use of data to inform educational practice". "These shortcomings indicate a systemic problem."
However, a spokeswoman for the directorate said this week the government was using the latest data to "identify broad areas of need across schools as well as to identify where we can provide more targeted support for individual schools".
"For example, the 2017 dataset confirmed a need to focus on early years literacy ... Similar initiatives have emerged in numeracy ... and high school writing."
She said the government was focusing on the data on student improvements over two years, which identified "strong performers like Charnwood-Dunlop Primary School".
"Through this lens, you can see that schools across Canberra are doing great things even where their raw academic performance differs."
Earlier this week, the public school teachers' union branded the My School website "a spectacular failure that is doing nothing for students".
ACT Education Minister Yvette Berry echoed some of the union's concerns, and is currently leading a national review of how the results are reported.
But shadow education minister Elizabeth Lee defended the website, saying she feared the government was trying to "remove parental choice and healthy competition in schooling".
"Every parent wants their child to get the best education possible. Comparative data on academic outcomes empowers parental choice and inspires healthy competition among schools to strengthen academic," she said.
"Of course it is also the case that compared to other jurisdictions, ACT academic outcomes have largely declined under the Labor government. This is embarrassing for the government and no doubt it is eager to remove anything that would highlight its own failures."