In this article, Associate Head (Teaching and Learning), Tim Dorning, discusses the findings of a recent Australian Council for Educational Research (ACER) report that used NAPLAN data to highlight differences in student performance based on whether students attended single-sex or co-educational schools.

Using St Michael’s Grammar School’s NAPLAN data, Tim Dorning compares our students’ performance with the schools included in the analysis over the same period, and concludes that St Michael’s students’ growth over time is greater than the growth seen in single-sex environments in both reading comprehension and numeracy.


If media reports reflect general public interest, then the three education-related topics that are front of mind within the community are standardised testing (in particular NAPLAN), single-sex versus co-education, and government funding.

Recently, the Australian Council for Educational Research (ACER) conducted an analysis of NAPLAN results to investigate differences in student performance based on whether students attended single-sex or co-educational schools.

The report titled, “Single-sex schooling and achievement outcomes”, provides a research base for a comparison of outcomes between single-sex and co-educational schools by utilising NAPLAN data from 2010 to 2012 (inclusive) as a measure of student performance. Interestingly, “All of the single-sex schools analysed were located within high or medium-high socioeconomic status (SES) communities.” In other words, these schools were comparable to St Michael’s in terms of their SES, which is a significant predictor of academic success.

At St Michael’s, our approach to NAPLAN testing is quite different to many other independent schools, as we don’t do any specific preparation for the testing. Our NAPLAN results therefore provide consistent data about what our students know and can do, rather than what they are able to “study up” for, allowing us to make evidence-based conclusions about the learning of our cohorts, relative to each other and to the wider population.

With this understanding, the findings of the report are interesting, but what is more interesting is when we begin to compare St Michael’s students’ performance with the schools included in the analysis over the same time period.

However, before we look at how St Michael’s compares to the single-sex and co-educational schools included in ACER’s analysis, it is important to note some of the key findings from the report:

In reading comprehension, “…at Year 3, boys’ schools were on average three terms of learning behind students in girls’ schools, but two terms of learning ahead of students in coeducational schools.

“By Year 7, this gap in reading achievement between students in boys’ and coeducational schools had reduced by half a term. The reduction in the learning gap was even greater in girls’ schools, with a loss of almost one term’s learning compared to students in coeducational schools.”

The researchers concluded that, for reading achievement, “Importantly, the narrowing gap in reading achievement as students progress by year level suggests that the value-add over time that is experienced in coeducational schools is not being realised in single-sex schools.”

In numeracy testing, “Boys’ schools were, on average, one school-term of learning ahead of students in girls’ schools, and one year of learning ahead of students in coeducational schools. Importantly, the differences in numeracy achievement remained the same between Years 3, 5 and 7, suggesting that there is no value-add over time to being in a single-sex school compared to a coeducational school.”

The two graphs below show the average score comparisons for girls’, boys’ and co-educational schools, over the three year period. These are given by the pink, blue and green lines respectively. We have added the heavy black line which reflects the performance of St Michael’s students over the same period.

reading comprehension NAPLAN

It can be seen that in reading, St Michael’s students followed the same pattern demonstrated for co-educational schools in achieving a larger growth over time than either of the single-sex school’s figures. In fact, at Year 7, St Michael’s students out-performed girls’ schools in Reading comprehension.


Whereas in numeracy performance, St Michael’s students did not follow the pattern of growth demonstrated in the research, instead they showed greater growth than all three averages. Additionally, it should also be noted that over the past three years, St Michael’s students’ growth in numeracy, as measured by NAPLAN from Year 7 to Year 9, has been the highest growth for our students within each cohort since NAPLAN data has been available.

Taking our analysis one step further, Table 1 (below) illustrates that the differences observed between genders in single-sex schools are not evident at St Michael’s. For example, in the 2016 Numeracy Test for Year 5, the data shows that girls only slightly out-performed boys (denoted by G>B JUST). It could then be concluded that these minor gender differences are due more to the nature of the cohort than to the gender of the students, as the greatest tested difference in any of the measures shown in Table 1 was approximately only one school term.

Table 1: St Michael’s Grammar comparison of boys and girls in NAPLAN testing

Year Y3 Reading Y3 Numeracy Y5 Reading Y5 Numeracy Y7 Reading Y7 Numeracy
2017 G=B G=B G<B JUST G<B G=B G=B

Apart from noting that the performance differences observed at the NAPLAN starting point (Year 3) for each of the three groups were more likely due to socioeconomic status factors than to school factors, researchers did not go on to suggest the possible causes of the effects they observed. Simply concluding that  there appears to be no value-add in numeracy achievement and even a decline in reading achievement over time in single-sex schools compared to coeducational schools.”

What the ACER report and our own analysis have highlighted, is that it is evident that St Michael’s students’ growth over time is greater than the growth demonstrated in single-sex environments in both reading comprehension and numeracy. This is demonstrated by both boys and girls in our co-educational environment.

Whilst we do not have any direct evidence as to why St Michael’s students perform as they do, one likely factor in the performance of our students is their engagement of creativity in learning. Emerging research is quickly demonstrating a link between engagement in creative learning and academic achievement, a principle that underpins St Michael’s teaching and learning philosophy.

Tim Dorning, BScEd, MEdStuds
Associate Head (Teaching and Learning)


Dix, K. (2017). Single-sex schooling and achievement outcomes. [rd] Research Developments. Retrieved from