The researchers in this study use the German National Educational Panel Study to compare data on the reading and mathematics scores of almost 1600 pupils in the upper and intermediate school tracks between 2010 and 2015.
Even after controlling for differences in students’ backgrounds and prior attainment, they find that those on the upper track make more progress in both subjects than those in the lower track, though the effect is greater in reading than in maths.
This is mainly driven by the average performance level in a class, and to a lesser degree by its social composition, they find. Neither the quality of teaching nor the ethnic background of the pupils is found to have a significant effect.
The researchers conclude that selection meets its stated purpose of increasing learning efficiency by sorting pupils into ability groups. But it also creates differences in attainment between pupils of similar abilities who find themselves on different tracks.