Are students drowning in the stream?

– Guest post by Dr. Michael Harvey @Doctor_Harves

recent education report from Tokona Te Raki has argued the streaming, also known as ability grouping needs to stop as it disproportionately affects the academic performance of Māori and Pāsifika students. Having now read the report, the paper does have a statistically significant conclusion that Māori does not have the same long-term outcomes as non-Māori, however, this is a correlation and not necessarily the cause of this underachievement.

So yeah, I decided to go down the internet rabbit hole and see what the global situation was and if indeed streaming was a major cause of Māori educational underachievement. First things first let me define my terms so anyone reading knows what exactly what I am talking about. ‘Streaming’ is used to describe a variety of approaches by which students with similar levels of current achievement (note I do not say ability) are consistently grouped together for lessons.‘Streaming’ can involve grouping students into classes for all or most of their lessons or only for some, in particular Maths, English, and Science.

In the New Zealand context, most students in different streams follow the same curriculum. The purported aim of streaming is to enable more effective and efficient teaching by being able to focus on learners with similar achievement in those subjects, in the hope to improve or enhance that achievement (think gifted and talented). Although this approach is sometimes described as ‘ability grouping’, I would see this more as ‘achievement’ rather than ‘ability, as schools generally use measures of current performance, rather than measures of ability, to group their students.

So after wading through the research (see the reference list at the bottom), just how effective is streaming? On average, students whose classes are streamed make slightly less progress than students taught in mixed achievement classes. The evidence suggests that streaming has a very small negative impact for low and mid-range achieving students and a very small positive impact for higher achieving students.  So, the effects are small, and it appears that streaming is not an effective way to raise achievement for most students although it is unclear whether the achievement at lower ends is due to streaming or other factors.

Other effects on students must also be considered, however, such as the effect on their confidence. I remember the effect on my friends at high school when they were told they were in 9J “stingray”, and being labeled stingers – the bottom feeders of the ocean. The research I looked at from the broader evidence base concludes that grouping students on the basis of achievement may have long-term negative effects on the attitudes and engagement of low achieving students, for example, by discouraging the belief that their achievement can be improved through effort and reinforcing the idea they were ‘born dumb’ and that intelligence is not malleable.

2012 OECD review concluded that streaming students is not associated with higher learning outcomes and that students from low-income families are likely to be negatively affected. Although the report did not go on to investigate the effect on local indigenous communities – though poverty is a large part of those community experiences globally.

But what of the actual research, is it reliable and can it be used to make inferences into best educational practice? The evidence on streaming that I read had been accumulated over at least 50 years and there are a large number of studies, some involving large student groups others with small. The conclusions on the impact of streaming are relatively consistent across different evidence reviews and meta-analyses. However, most of the reviews present relatively basic analysis and few investigated the different pedagogical approaches being used in the different extremes of the streamed classrooms. They do not explore whether effects vary between different interventions and the evidence base would benefit from new reviews which address these issues in more depth. Overall, the evidence is rated as limited.

One example of this is that the majority of the experimental evidence comes from the USA, and there are few rigorous experimental studies from other countries like New Zealand and the impact on indigenous communities. There was more evidence from secondary schools than primary schools, as streaming is more commonly used for older students. 

So there, you go, streaming has a small effect either way on overall learning for both low ability and high ability groupings and there is little support for the claim that streaming is the cause of Māori or Pāsifika underachievement – though such research is scant either way. So we must look to develop our pedagogy as educators to cater to the diverse needs of our students, no matter their present achievement 


Collins, C. A., & Gan, L. Does Sorting Students Improve Scores? An Analysis of Class Composition.
(No. w18848). Cambridge, MA: National Bureau of Economic Research. (2013)

Duflo, E., Dupas, P., Kremer, M. Peer Effects, Teacher Incentives, and the Impact of Tracking: Evidence from a Randomized Evaluation in Kenya American Economic Review 101 (5): pp 1739-1774. (2011)

Dunne, M., Humphreys, S., Dyson, A., Sebba, J., Gallannaugh, F., & Muijs, D. The teaching and learning of pupils in low-attainment sets. Curriculum Journal, 22(4), 485-513. (2011)

Hallam, S., & Ireson, J. Secondary school pupils’ satisfaction with their ability grouping placements.
British Educational Research Journal, 33(1), 27-45. (2007)

Hanushek, E. A. & Woessmann, L. Does educational tracking affect performance and inequality? Differences-in-differences evidence across countries. CESifo working papers, No. 1415. (2005)

Henderson, N. D. A meta-analysis of ability grouping achievement and attitude in the elementary grades
Doctoral dissertation, Mississippi State University, Mississippi: Department of Curriculum and Instruction

Ireson, J., Hallam, S. & Plewis, I. Ability grouping in secondary schools: Effects on pupils’ self-concepts.
British Journal of Educational Psychology 71. 2, pp 315-326. (2001)

Ireson, J., Hallam, S., Mortimore, P., Hack, S., Clark, H. & Plewis, I. Ability grouping in the secondary school: the effects on academic achievement and pupils’ self-esteem. Paper presented at the British Educational Research Association Annual Conference, the University of Sussex at Brighton, September 2-5 1999. (1999)

Kulik, J.A., & Kulik, C.L.C. Effects of ability grouping on student achievement. Equity and Excellence in Education, 23(1-2), 22-30. (1987)

Tereshchenko, A., Francis, B., Archer, L., Hodgen, J., Mazenod, A., Taylor, B., Pepper, D., & Travers, M. C. Learners’ attitudes to mixed-attainment grouping: examining the views of students of high, middle and low attainment. Research Papers in Education, 1-20 (2018)

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