The revelation that some primary schoolchildren spend far less time being taught core subject such as maths and English once again raises a vexing question on education.
Judging by the findings of the latest ESRI report on the raw data produced by the Growing Up in Ireland Survey, it would appear that some primary school children receive as much as two hours a week more maths teaching than others. This "learning gap" can have huge implications for schoolchildren when they proceed to second level education.
In addition, the ESRI report found that pupils in fee-paying schools and single-sex girls' schools were likely to spend the most time being taught core subjects. It was also these pupils who were most likely to be taught using the new interactive teaching methods.
Perhaps not surprisingly, it was pupils in disadvantaged areas, particularly boys, who tended to receive the least amount of teaching in core subjects and were also most likely to be taught using traditional teaching methods.
The publication of the ESRI report is timely, coming as it does in the wake of the controversy generated by the cutbacks to the DEIS (delivering equality of opportunities in schools) scheme announced in the Budget.
The report has also triggered a response from the teachers' unions about class sizes with INTO general secretary Sheila Nunan pointing out that one fifth of all primary schoolchildren are still in classes of 30 or more pupils.
However, these only go some of the way to explain the situation.
It is possible to examine the ESRI report and conclude that there are some teachers, most of whom seem to be teaching male pupils in disadvantaged areas, who have not changed with the times and are still using old-fashioned teaching methods and spending insufficient class time teaching the vital core subjects.
While teachers have to do their work under a wide range of differing conditions and pressures, there are bound to be those on foot of the ESRI report who would claim some teachers suit themselves rather than their pupils in their choice of teaching methods and the amount of time they devote to teaching core subjects.
This can be countered by the argument that quite often, to paraphrase an old saying 'teacher always knows best'.
The INTO and the other teaching unions are happy to talk about reform, embracing programmes such as DEIS and the extra budgets that come with them.
They, like so many other professions, are aware that there has to be meaningful change in the classrooms to gear students for a world that is changing dramatically.
But alongside this they retain the awesome responsibility of delivering the foundations of a real education.