Oh, big new education practice. Highly recommended in education schools, as are group work and projects.
Meanwhile, research shows that the tried & true method of lecture & explanation, then practice, is the best way of imparting information. Odd that it's not the method the ed schools or the administrators recommend.
Being sure that certain subgroups "get it", and the elimination of tracking in school systems these days (it was phased out of my school district 8 years ago) means that the class must not progress through material at any rate faster than what can be absorbed by the slowest students. This means that the fastest students will not be challenged in the course room.
They had to eliminate tracking here years ago because the courts decided it was de facto segregation - there were more minorities in the lower classes. If it could be used, and if it were used correctly, it might be part of the answer - give the slower kids the extra help & remedial services they need.
One of my children was gifted & not being challenged at all - and was becoming a behavior problem from sheer boredom. I had to push for gifted services for him. Parochial school would have been a nice option, had there been any nearby.
Likewise, it has long been known that the best time to start foreign language instruction is in the early grades, where kids can pick it up effortlessly. Yet in the public school system, kids don't get any until high-school
A friend of mine was talking to a friend of hers, who teaches at a private school for very well-to-do families. There, they do language instruction starting from first grade. My friend asked the teacher why this wasn't done in regular schools. Her reply: "One does not give servants the keys to the master's bedroom." I'm not making this up.
Call me tinfoil-hatted, but the only explanation that makes sense to me is that there is a deliberate and conscious effort to sabotage the education of public school kids, so that the gifted middle-class kids will not be competition for the kids of the elites. I worry all the time about what I could do to make my kids more competitive in the 21st century. I'm sure that parents among the elites must also be thinking about what they can do. And I would not be surprised if more than a few conclude that, while there is a limit to how well fertilizer will make their saplings grow, a chainsaw may be effective in making sure they are taller than any competition