"There is no single magic characteristic," researchers from Glamorgan University say.
As Scots this week wrestled with the fallout from the publication of primary test results (page one), a detailed study of 18 Welsh primaries in disadvantaged communities, whose test scores were in the upper quarter of all results, shows that they held common features, the prime being their "productive, strong and highly inclusive culture".
The researchers say schools focused on effective teaching and learning for all with a "powerful emphasis on enabling the pupils to attain high scores in national curriculum tests and providing the pupils with an enriched curriculum". They worked hard on how children learn and encouraged them all to achieve.
One headteacher said: "It all comes down to teaching in the classroom."
There was no common arrangement in classes, which contained wide variations in abilities.
The study, Narrowing the Gap in the Performance of Schools Project, which was backed by the Welsh Assembly, found that schools concentrated on literacy and numeracy, used a wide range of learning activities, valued creativity and new technologies and kept pupils busy.
"Not a minute is wasted," one teacher said.
The researchers say teachers planned their lessons thoroughly and often worked collaboratively, which "contributed to the sense of consistency and stability for the pupils, which in turn increased pupil confidence".
Teamworking, including assistants and nursery nurses, was a feature.
Teaching and learning were monitored carefully and learning was regularly assessed in different ways. Target-setting for pupils was important and they were encouraged to mark their own work.
"The schools were open to ideas to enhance learning but were not desperate to try new initiatives," the study states.
The researchers say schools were successful because of what they did and the way they did it. "None of the characteristics can be singled out as the vital ingredient. All the characteristics contribute to success."
Strong leadership by headteachers in "setting, driving and reinforcing the schools' cultures" was important as was the "mindset" of the school.
Schools were said to be optimistic and teachers "highly reflective about their work". As one teacher said: "We cannot let those kids down." Another said: "There are no lids on kids here."
The primaries that made gains were strong on effort, praise and achievement and displayed a caring ethos. Extra-curricular activities and good links with parents were other factors in creating the right climate.
In their recommendations, the researchers advise all primaries that they can make a substantial difference to attainment in areas of high social and economic disadvantage but that they need the support of the local authority if they are to succeed.
Motivation of staff is crucial. "More attention should be given to motivating all those who work in schools by praising their efforts, inspiring them and actively encouraging them to do even better," they say.
The study points out that statutory testing is now being removed in primary schools and the focus is switching to "moderated and accredited teacher assessment" and skill tests for pupils in Year 5.
How one North Ayrshire primary turned it around 8 The report is available on www.learningwales.gov.uk.