Yes, and ability grouping is not only free but can save money. A teacher can handle more children in a class when the ability range is narrower. The government school monopoly is run as much for the benefit of the unionized teachers as it is for the students. The teachers unions oppose labor-saving practices.
The underlying assumption everyone (including teachers) seems to have is that public schools are for producing academically successful students who will go forward and have successful careers.
Sadly that is now how our public education system was designed. It was designed to produce moderately educated citizens, and (more importantly) obedient factory workers. This is still apparent with the loud school bell system, having children form straight lines, sit in identical chairs doing identical work.
If your purpose was to truly educate and help children grow and mature, think of how you would design a school. I highly doubt anyone would come up with the system we've got now.
