From the comments:
If you asked scientists to design the worst possible system to educate masses of young people, they would come up with the system that much of the US has arrived at.
Drag them out of bed at 6am and send them home at 2:30, completely conflicting with their parents’ schedules and flying in the face of research that shows how much sleep kids need. Bonus points if some kids have their “lunch” at 10am.
Plop them in desks and force them to listen to adults of highly varying skill level who might have no idea how to hold the attention of 8 or 10 or 15 year olds. (In this case, blame it on the kids for being layabouts.) Even better, make these adults live in constant fear of unwanted reassignments, give-backs, or layoffs, especially the newest ones who may already be least equipped for success.
Convince the populace that teaching is a profession for losers who don’t deserve the middling salaries they already get. Extra points if you can build resentment toward teachers for having health benefits.
Resist efforts to identify the best performing and worst performing teachers. When such efforts are undertaken, use the most simplistic criteria possible, such as student performance on a small handful of arbitrary tests.
Focus all student effort on the material contained on those tests. At least 50% of this material should be a poorly-constructed, relentlessly sequential math curriculum with little to no articulated connection to the real world, and which ought to doom large swaths of kids to failure from the beginning.
Strip away physical activity, including gym class and recess, despite the fact that we know physically active kids do better. (Oh, plus that whole obesity epidemic, which might be effectively countered with a concerted effort to get schoolkids to be more active and learn basic fitness techniques).
Also, eliminate anything creative, such as art and music, despite the fact that we know these things are highly effective at keeping kids engaged with the whole school experience and getting them to do better in other subjects.
Cut budgets at every stage, from building construction to basic supplies, to the point that many schools are decrepit prisons with little natural light and not enough markers for the whiteboards. Very inspiring, very conducive to learning.
Divert a little bit of money to inflated salaries for underqualified administrators, just enough to get citizens to convince themselves that schools are awash in money and budgets need to be cut more. Make school budgets dependent on what citizens think of their local government’s performance on unrelated issues.
Then, when all of this has been accomplished, let the kids all go home for three months with virtually no attempt to encourage off-site learning or retention of previous material.
If your school is in a particularly low-income or high-minority area, this entire process should ideally be infused with an atmosphere of hopelessness so complete that people who haven’t witnessed it can not imagine the degree of despair that rules every day.