Figures published today show that, nationally and in the 16 education authorities involved, pupils' performance in reading and numeracy in P3 and P5 is markedly better than at P7 and S2.
The Scottish Executive now suggests that, as those who began attending pre-school in the late 1990s start to arrive in P7, the results for that stage should show signs of further improvement.
The SSA report, based on results from tests administered to 28,000 pupils in 1,300 schools last year, says the survey of P3 and P5 classes is "particularly encouraging, suggesting that their recent approaches to raising attainment in the early years might be having a positive impact on attainment in reading, particularly for lower achieving pupils".
The executive is cautious about comparing these results with the previous 5-14 surveys and the Assessment of Achievement Programme, because the tests are different.
While the executive is keen to laud the emphasis on early years learning for later improvements in primary, it is less certain about the explanation for the long-standing dip in performance at S2.
One suggestion is that the targets for S2 may be too difficult, as 65 per cent or more of the answers have to be correct for pupils to be described as "very good" or "well-established" at their level.
The survey also notes primary teachers rated their pupils' attendance, motivation and behaviour twice as highly as secondary teachers did their S2 pupils.
SSA results 4, Leader 22