We've been there. Our DD would rush through assignments to get them over with, because they were boring. Her previously beautiful penmanship became unreadable. She'd start on her work before reading the directions. She's race through and make simple errors of grammar, spelling, or arithmetic, and never look back. And then she'd have meltdowns each time she received a justly-deserved F.
All while we were pushing them to accelerate her, too. It just gave them further cause to deny her an appropriate challenge, which is exactly what she wanted and needed.
So... bribery. For every paper that came home from school, we offered her a dollar for every B, and two for every A. C's and D's earned her nothing, and an F would mean she owed us a dollar.
It had the desired effect, as DD began to feel a reason to do well on mundane, boring assignments. She learned to slow down, read instructions, and check her work. Her penmanship has improved to legibility, which is all I care about. She has since proven all of her detractors at the staff wrong about skipping her, she's on the honor roll, and she takes enough pride in her work now that the incentive program is no longer necessary.
We still do it, though, because it gives her a way to "earn" her own money and practice money management, which is a necessary life skill. And as an unexpected side bonus, it also cuts out a lot of "Buy me that!" nonsense, because we can end those arguments by insisting that she buy it herself. We've dropped the negative F impact, because on the extremely rare situation where she brings one home these days, it's usually because she was in a pull-out when the teacher lectured on that particular subject.
