We now return you to a discussion of government schools... might a change from grouping by chronological age, to flexible cluster grouping by readiness and ability, benefit both students and teachers?
Yes. However, that would require such a paradigm shift in the public education system that I cannot believe it would ever happen.
That said, we saw exactly what you described in our former town's Montessori school. It worked very well, but the school was small and many people want a big school and associated amenities for their children. Thus the school struggles financially most years.
I have the opposite view. The fiscal reality is that, in most of the developed world, demographic change will necessitate a shift in resources away from programs serving the young toward end-of-life support. Like it or not, the public is going to have a bitter pill to swallow in making choices about what to prioritize. Sadly, voters tend to be myopic and cut value-generating resources at the expense of consumption.
In my province in Canada, education will butt heads with our sacred cow, public healthcare. Because boomers carry the political clout, and health costs are expected to consume 70% of every dollar of public revenue in 5 years, we can read between the lines about what the priorities are. It ain't special education! Gifted public programs are being shuttered faster than you can say "inequality".
Economies of scale are needed to make ability-grouping viable, and public schools have scale in spades. Schools are averse to change when it means rallying new resources, but ability-grouping leverages pre-existing resources more efficiently to better meet the needs of all students. So while I agree it's a total paradigm shift, I believe the fiscal backstory makes disruptive change in public education necessary for its survival.
