"too costly for most societies to bear on a large scale" this is changing as we speak with language models.
https://www.amazon.com/Education-Automation-Freeing-scholar-...
It's not that these cannot happen alone, via self-directed (autodidactic) study, or with the assistance of technologically-mediated aides. But time and again the effectiveness of such methods falls far short of direct human instruction.
LLM AI chatbots can respond to written or verbal cues, to an extent, but as yet lack an underlying pedagogical framework and understanding of the context of a communication.
From what I've seen so far of such models, "lacking an underlying framework", the bones and skeleton of a conversation, if you will, which can be subsequently fleshed out, seems to be a general failing of the models, so far.
I'm not saying that this cannot emerge, and parts of this may in fact be a relatively simple additional step or advance. Given other advances such as sentiment and mood assessment and analysis they may even be largely in-place. What's left however is the motivation of such efforts, and alignment with the educational mission, again a place where previous technological education programmes have foundered, as most have been coopted by, if not outright conceived as, propaganda and cultural programming tools. (A part of traditional education as well, but far less effectively and uniformly delivered when mediated at 1:15 -- 1:30 or so ratios amongst millions of instructors[1]). It will all but certainly be difficult for corporate-based LLM models to resist such temptations, see the earlier case of Backrub and perverse incentives.[2]
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Notes:
1. Figure based on an off-the-cuff estimate, though substantiated by US Dept. Ed. statistics, see: <https://nces.ed.gov/fastfacts/display.asp?id=372>.
2. "The Anatomy of a Large-Scale Hypertextual Web Search Engine" (1998), Appendix A: <http://infolab.stanford.edu/~backrub/google.html>
But time and again the effectiveness of such methods falls far short of direct human instruction.
How human teachers perform relative to some abstract ideal isn't particularly interesting if that ideal isn't viably attainable. All pedagogical methods are relative.
Teaching efficacy does of course vary, though most studies show that other factors, including both environmental (e.g., student's home life, parents, neighbourhood, income/wealth) and institutional (school or district as a whole) matter far more than any individual teacher.
This is a key point in Cathy O'Neill's book Weapons of Math Destruction, mentioned in her Ted Talk here (at about 3 minutes): <https://yewtu.be/watch?v=_2u_eHHzRto>. Of NYC public school teachers tested, 665 had two scores, for which there was virtually no correlation.
Keep in mind that "institutional factors" frequently involves "eliminating educationally-disadvantaged students", by many methods. One such discussed in the past month at the New York Times, "How Educators Secretly Remove Students With Disabilities From School" (10 Feb 2023) <https://www.nytimes.com/2023/02/09/us/students-disabilities-...>
There's a long history of ed-tech failures. You might find Failure to Disrupt: Why Technology Alone Can’t Transform Education by Justin Reich to be a useful introduction:
<https://cmsw.mit.edu/failure-to-disrupt-why-technology-alone...>
In kindergarten he became eligible for special education for what school officials described at the time as a “communication disorder,” but they opted instead to place him in a regular classroom and have him pulled out for instruction in a smaller group.
And later in the story, on the same case:
A few weeks later, the school team emailed Ms. LaVigne to set up another meeting, offering to add one class to Dakotah’s schedule in December.
Note the language "school officials" rather than, say, "a teacher".
Similarly in the second case described:
Records show that the Sacramento City Unified School District has a history of disciplining students with disabilities, particularly those who are Black, at a higher rate than most other public schools in the state.
Rather than get hung up on the specifics of one specific story that happened to come to mind, you might want to consider the general dynamic and other modes of student segmentation as well: segregated schools, charter schools (with selective admissions criteria), voucher programmes, and the like.
Again: all change the overall nature of the school far above and beyond the specific teaching abilities of any given instructor. A school or district whose policies and practices permit exclusion of challenging students isn't improving teacher's pedagogical skills, but rather selecting whom specifically they're permitting to be educated there.
Different educational modalities and/or intensive education might be another approach. That isn't what the story is describing or what you seem to be proposing.
It's an interactive e-book, of sorts.