I would tend to go with blackcat on this one - though I will readily admit that many parents think I am way too easy on my kids. But their kids don't have ADHD, and ADHD is crazy making. There is just nothing that looks so volitional. Obviously she can do it - she did it perfectly the whole first semester, right? Obviously, she's just not trying anymore.
Well, maybe.
Or maybe it took everything she had, plus the right alignment of the planets, to pull it off last semester, and now she's exhausted and overwhelmed and it's just become too much. Or maybe the nature of the work changed, or the volume, or the timing, or the writing demands, or Mars is rising in Jupiter....
I have really, truly been convinced that it's true: kids do well when they can. A mountain of LD and 2E report cards to the contrary, lazy and unmotivated are not natural states for kids. They want to please us. They want to feel good about themselves. Even 12 year olds. And if they're deliberately self-sabotaging, well, that's just another way of showing that they are facing a barrier that feels so unsurmountable they're afraid to even try.
So my personal two cents worth is - scaffold like crazy, but put her in charge. You make lots of suggestions, but as much as she is currently able, she makes the decisions, and she owns the plan. Your younger DD is your super visual-spatial one, I think? My DS is too, and I am so not. So this is the hard part for us: my super linear, verbal methods (yup, I love lists) don't work worth a darn for him, but it's really, really hard for him to come up with ideas himself of what would work for him on his own. So we have to keep experimenting, and we continue to search for what will really work. A teacher with electronic assignment tracking is worth their weight in gold. (Our latest challenge is figuring out how to study for tests, a skill he's never needed before - - - but that's a whole other post.) Given the state she is in now, I would suggest you over-compensate at the beginning, but explicitly talk about about the step-wise removal of pieces of the scaffold over time (potentially a looooong time), and how she might know when she is ready to take over the next bit for herself.
As I have written before, I have found out the hard way that avoidance is a deadly habit, and becomes its own reward. You don't want to punish for disability - but you do want to make avoidance more painful than the alternative - doing the work. So consequences for executive function failure, no. But consequences for refusing to engage with and own the scaffolding, yes. But I would start gentle - it sounds like she may be pretty deep in a hole right now, and need a lot of help just digging herself out before she can see the light of day. Anxiety has huge impacts on our ability to think, judge, and make good decisions. (In fact, anxiety can manifest a whole lot like inattentive ADHD, so you may have some chicken and egg happening here. If her anxiety is that high, she may truly not be capable of making good decisions right now.)
If she has a particular teacher whose good opinion she values, it really helps to be able to work in partnership. DS (almost 13!) worships his teacher, who is awesomely supportive but also seriously hard-core about 'grow up and shape up'. It's occasionally disconcerting (you do understand he can't do this on command, right? Yes, I do agree he's behaving like a kid several years younger when it comes to EF - and you do understand that's pretty much textbook definition of ADHD, right? No, actually, the teacher doesn't, but I've made that aspect my problem and our good cop/ bad cop act is helping a lot). I agree that yes, DS does have to try lot harder. But what he has to try a lot harder at is understanding his weaknesses, and owning the need to build and adhere to scaffolds that enable him to compensate. He does not have to try harder to make EF functions appear out of thin air. Yes, he is absolutely accountable for his choices and avoidance will not be tolerated - but he is only accountable for those things which actually are choices, the behaviours he can control.
This is, of course, a lot easier said than done. A lot of what I and DS's teachers have done over the years trying to help him just enabled his avoidance. The distinction I make above is not terribly clear in real life. But we keep trying, and we're getting better at it.
So bottom line - - - trust your gut. No one else has all the info you do. If you think she needs help rather than punishment, you are probably right. Maybe see if you can identify what changed since the first semester - is there anything different about the workload that means she needs some different kinds of supports now that weren't essential then? Or maybe it's just the anxiety of trying to keep up slowly built up over time, increasingly challenging her compensation mechanisms until it overwhelmed them - so the change sees sudden from your end, but not from hers. In my experience, when 2E kids hit the wall, it can look pretty sudden from the outside, but the struggle may have been growing, invisibly, for a long time.
