Classroom streaming – the separation of students into classes based on their prior attainment – is currently a topic of debate in New Zealand. Some commentators have called for the practice to be banned. The Ministry of Education would like schools to abandon it voluntarily.

In this report, the authors examine New Zealand-based and international evidence on the effects of streaming on students’ learning. The main findings were: 

• Greater gaps between higher and lower achieving students are commonly found in schools that stream than in schools that don’t.
• Increased educational inequality in streamed environments may be attributable to differences in teaching and curriculum rather than to streaming directly.
• De-streaming has its challenges. Unless appropriate changes to teaching practice accompany it, it can do more harm than good.
• The effects of streaming on students’ learning vary across subject areas.

The guidance in this report is specific to streaming, but the basic wisdom is general: for good policy, define transparent objectives, consider multiple perspectives, collect more data and use proven quantitative methods before acting. This wisdom would be well headed in New Zealand, where there is a history of adopting education policies, often prematurely, with far-reaching negative or unintended consequences.