There would be no Department of Education.
Well, we wouldn't be giving tax dollars to private school students, that's for damn sure.
Grade level advancement would be earned by learning, not by calendar.
All students would receive a free, quality lunch (nachos not an entree, not everything out of a big tin can, etc).
Teachers would be paid very well, which would attract better prospective teachers.
Multiple choice questions would be banned.
Funding for each school would be made at the county level, not at the neighborhood level.
We wouldn't have monies so separated (now there's often plenty of money over here, but none over there).
Poor teachers either improve or are let go (this is how it is wherever I've been, but sorry, no, tenure shouldn't be a thing).
First-year teachers are given curriculum and teacher editions to help them along, but once they've shown to be a quality educator, they're free to branch out and do more/better than that.
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*If you improve the schools people opt out of today, there's no reason for them to need a voucher for someplace else (by and large).