SOR, good point!  When I first started teaching 40+ years ago (now retired), students were grouped homogeneously in the core subjects like English, Science and Social Studies.  Homogeneous grouping simply means by ability.  A decade or so later, like many educational policies, the pendulum swung in favor of HETEROGENEOUS grouping where students of any ability are placed in a classroom.  The theory there is that the "good" students will be like role models for the poor students, and that they will help the poor students achieve.  Hard to believe, but that was and still is the trend.  My department included 15 people, and when we voted, the final vote was 13-2 in favor of hetero.  Just me and another teacher voted NO.  I transferred to another position.