The teacher treats every student the same and never plays favorites.
Tips
usage
This reading carries the figurative sense: treating one side generously and the other shabbily. It is a short form of 厚此薄彼 and turns up mostly in the negative, as 不分厚薄 or 没有厚薄. Physical thickness is the other reading, hòubáo.
mistakes
Here 薄 takes its literary reading bó, the one in 刻薄 and 厚此薄彼, where it means slight or grudging. The everyday báo reading belongs to physical thinness, so a plate of steel is never measured in hòubó.