How?
A big difference between 19th century / early 20th century education, and current education, is the insistence on educating children that are disruptive or destructive of the educational environment. Or educating children that demonstrate a distinct desire to NOT be educated.
There's been a shift in the last 30 years, sacrificing potential top achievement with the intent of bolstering middle-to-low achievers. Part of that shift has been reticence to fail students that don't achieve objectives. Part of that shift has been lowering of standards for all students. The net result is bored bright kids, less top tier subject level mastery, and more disruptive elements being compelled to remain in an environment they clearly don't want to be in.
Some people aren't capable of a High School education. Particularly if you measure it by pre-Federalization standards.
Make a HS Diploma have value again. Fail kids that don't deserve it.
Failing elementary schoolers that demonstrate traits of kids that will grow up to be high school disrupters will give them a shock and a social stigma. Some people take being held back as a lesson. Some people just need it. And some people just can't cut it and need to be culled.
Here's the thing: Regardless of education standards, the market will have the same number of jobs available, and the same degree of entrepreneurship available. Browbeating a disruptive kid into staying in "school" until he "graduates" (even though he can't read on a 4th grade level) doesn't mean that person is any more valuable to an employer than a disruptive kid that is kicked out of school at age 14 (after being held back several years) and has no diploma. He's still gonna be a fry cook at the local McDonalds.
So what's worth more? An education system that "graduates" a near 100% population of morons? Or an education system that graduates 75% of the population, perhaps 10-20% of which are well versed in Calculus, CAD, basics of the classical sciences, and are solid communicators both oral and written?
This is also how you attack degree-bloat. Not only do you make a HS Diploma valuable again, you make the GPA and selected coursework something people pay attention to. I'd take one of those 10% HS graduates from my hypothetical system well before I'd take a DeVry or U-Phx graduate under the current system. I can train someone naturally bright to do anything. I can't train a "system gamer" that does the minimum required work to get by.