I don't have experiences with accommodations at school specifically for migraines (although I do have experience with migraines so I can empathize with your dd!).. but we have had extended time for assignments as an accommodation for my ds. Extended assignment time can be handled in different ways - the two we have experience with are turning in the assignment one day after the reason it's late has ended (in this case absence due to migraine or migraine during work session at school), and in another instance ds had an accommodation where he could wait until the weekend to make up missed work. The thing to think through is what your dd's homework load is like *without* missing work due to migraines - if she has a ton of homework on school nights or has a busy schedule during the week with after school activities, it's helpful to be able to wait until the weekend to catch up with homework if she needs to. The other thing to add in is giving the student an out of being able to ask for an extension if needed due to total homework load when they are trying to make up an assignment.
Another request you could make is a reduced workload for assignments - for math problems, for example, the teacher could allow her to do every other problem or just one of each type to show she knows what she's doing. For writing assignments, you could ask that she is allowed to write for a certain length of time and can then stop. Those types of modifications are a little outside of just asking for extended time, and as I mentioned, my ds had them for other reasons... but they are accommodations that let a student complete homework without penalty so if they sound like something that might work for your dd you could request them.
I am also sure you've already thought of it, but I would request an accommodation allowing her to go to a quiet place when a headache starts. And I'd google 504 accommodations + migraine
Sorry your dd is having to deal with the migraines.
polarbear
