Huh, I'd liken school in those grades to a series of meetings basically all day, that are mostly presentations, every day of the week, with a lot of restrictions and harsh conduct & expectations from the people leading the meetings, which'd never fly in an office. Often with terrible lighting and long stretches without seeing the outdoors, even though a window. And crazy-early start times that may have you not seeing the sun until 3PM or so, for months. And, especially toward the end, a couple more hours of work at home every day. Mostly of math problems.
Also, all that, plus you're not getting paid for it.
Also, all that, plus you're not getting paid for it.