NO SURPRISE HERE: Ability grouping helps top students, and doesn’t hurt weak students.

Strong students learn less math in mixed classes, concludes a new Education Endowment Foundation study of English middle schools, reports Richard Adams in The Guardian. Weaker students, as judged by prior math achievement, do about the same whether they’re in mixed classes or lower-track classes, University College London (UCL) researchers found. Furthermore, students placed in lower-track classes were more confident of their math abilities than those in mixed classes.

The “big and important” results “support achievement grouping in maths,” said John Jerrim, a UCL professor who has studied mixed-ability classes but wasn’t part of the study, Adams reports. Jerrim added, “It wasn’t long ago that some educational researchers in the UK and Ireland were calling ability grouping ‘symbolic violence’.”

High achievers grouped by prior achievement made two months more progress on average than similar students in mixed classes, the study found.

Not that long ago, this was common knowledge and common practice.