Lots of good advice here. Let me offer some more information/response to some comments...
1. In regards to her not understanding the work. I have not focused a ton on this idea. Mostly due to the fact that the work she is not doing is pretty easy classwork. It's not obscure math problems, but related more to social studies "reading & answer" type work. Honestly, most of the issues resolve around work that is not super complex. Also, for instance, she had two major incomplete assignments I found online last night. After finding the paper in her backpack (which the teacher returned to her), there was one sentence filled out. The rest is not done. This was "reading & answer" questions. The teacher emailed me this morning that she was the only one to turn it in mostly blank (even though they worked on it in class for 3 days).
2. Maybe I am being too involved, which has taken away her ability to do it on her own. But I swear this has not how it's always been. I have let her be independent in her decision making and school work since a young age. It has just been the past 2 year's that I have had to become this nagging father (which I hate).
3. The teacher stressed to me that he believed she was very smart and could be an AP student. He thought her lack of completion/missing work was strictly related to her "not paying attention" or "being distracted".
4. To another poster, maybe she is bored of the work. Again, an interesting thought. Not sure how I come up with a solution to that other than continuing to explain the importance. Also, she has been very blunt before and said that school was just boring. Of course, what kid hasn't thought that or truly believes that. I know I did, but I worked hard to ensure things were done.
5. I have really tried not to punish a ton. I'm not perfect in my responses or conversations with her, but from a consequence standpoint, she has really had it easy. Her mom doesn't like hard consequences, which has swayed me in that direction as well.
6. The longest I have taken her phone away is 1 full day. This has been meaningless in my mind as well. Her mom thinks I'm unfair if much longer. I have now, however, told her for each piece of missing work, it will be 3 full days (which she received last night)
7. To "hs teacher". Your comments are exactly what I'm trying to do. Thanks. However, to be honest, I'm doing it daily and not weekly. Maybe this is too much. Maybe it's making her really despise it all. However, I had to start doing this due to the fact that 1 day without me watching/checking/organizing, things go haywire.
8. She is involved in afterschool activities, which I was hoping would actually help her stay motivated to do well in school. It doesn't seem like it's working though.
9. She can be pretty lazy. Just in general. Amazing kid, but the lazy bone is there. I've honestly wondered if this relates to her just being lazy and not wanting to do things that seem "boring". Of course, that could be me being a jerk.
10. Her mom views things differently. She thinks maybe it's ADHD. She also think I nag too much. She thinks taking away her phone more than 1 day is not right. She thinks I'm not taking into account other things she might have going on in her life at this age. I try to have an open mind, so she could be right in some cases. I'm trying to take all things into account when pursing the right solution.