The ideal school lets every student learn at their own pace, using a tablet with pre-recorded lectures and computer-graded quizzes. Instead of lecturing, teachers tutor small groups that did poorly on the same quiz, to help them understand the material and progress. This is the mastery learning model [0]. Classroom experiments have shown that mastery learning students learn much more with the same time spent with teachers [1] [2].

This shows that society knows how to educate children equitably and at scale. Unfortunately, it doesn't do it.

[0] https://en.wikipedia.org/wiki/Mastery_learning

[1] http://web.mit.edu/5.95/readings/bloom-two-sigma.pdf

[2] https://news.ycombinator.com/item?id=18105487